Methods of treating skin disorders using an il-31ra antagonist

ABSTRACT

The present invention relates to methods of treating patients suffering from Contact dermatitis, Drug induced delayed type cutaneous allergic reactions, Toxic epidermal necrolysis, Cutaneous T cell Lymphoma, Bullous pemphigoid, Alopecia aereata, Vitiligo, Acne Rosacea, Prurigo nodularis, Scleroderma, Herpes simplex virus, or combination by administering an IL-31RA antagonist.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent Ser. No. 11/353,451, filed Feb. 14, 2006, which claims the benefit of U.S. Patent Application Ser. No. 60/716,761, filed Sep. 13, 2005, U.S. Patent Application Ser. No. 60/694,867, filed Jun. 29, 2005, and U.S. Patent Application Ser. No. 60/653,283, filed Feb. 14, 2005, all of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

The skin plays an important role in the immune system and consists of layers. The epidermis is a surface layer. Underneath the epidermis is the dermis, a layer of connective tissue. Underneath the dermis, is the hypodermis, a layer of large amounts of adipose tissue. Circulating T lymphocytes migrate to the skin under normal and inflammatory conditions. The cutaneous lymphocyte antigen (CLA) is considered a homing receptor for T cells with tropism for the skin. Santamaria-Babi, L., Eur. J. Dermatol. 14:13-18, 2004. CLA is a carbohydrate structure which is expressed on memory T cells as an epitope of the single cell-surface protein named P-selectin glycoprotein ligand-1 (PSGL-1) and facilitates binding of T cells to E-selectin, an inducible adhesion molecule expressed on vascular endothelium. See Fuhlbrigge R C, et al., Nature 1997; 389:978-81.

Several diseases of the skin are known to express high levels of CLA+ T cells, including atopic dermatitis, contact dermatitis, drug-induced allergic reactions, skin-tropic viruses and viral associated pruritis, vitiligo, cutaneous T cell lymphoma, alopecia aerata, acne rosacea, acne vulgaris, prurigo nodularis, and bullous pemphigoid. There is a need to treat such skin T cell mediated diseases.

The demonstrated in vivo activities of the cytokine family illustrate the enormous clinical potential of, and need for, other cytokines, cytokine agonists, and cytokine antagonists. The present invention addresses these needs by providing a method of treating such diseases with IL-31RA antagonists, e.g., IL-31RA soluble receptor or neutralizing IL-31RA monoclonal antibody or fragment, a receptor for the newly identified IL-31 cytokine. IL-31, when over-expressed in mice, results in dermatitis-like symptoms. Both skin-homing T cells and epidermal keratinocytes have been implicated in the pathology of skin diseases in humans.

The present invention provides such polypeptides for these and other uses that should be apparent to those skilled in the art from the teachings herein.

DETAILED DESCRIPTION OF THE INVENTION Definitions

Prior to setting forth the invention in detail, it may be helpful to the understanding thereof to define the following terms:

Unless otherwise specified, “a,” “an,” “the,” and “at least one” are used interchangeably and mean one or more than one.

The term “affinity tag” is used herein to denote a polypeptide segment that can be attached to a second polypeptide to provide for purification or detection of the second polypeptide or provide sites for attachment of the second polypeptide to a substrate. In principal, any peptide or protein for which an antibody or other specific binding agent is available can be used as an affinity tag. Affinity tags include a poly-histidine tract, protein A (Nilsson et al., EMBO J. 4:1075, 1985; Nilsson et al., Methods Enzymol 198:3, 1991), glutathione S transferase (Smith and Johnson, Gene 67:31, 1988), Glu-Glu affinity tag (Grussenmeyer et al., Proc. Natl. Acad. Sci. USA 82:7952-4, 1985), substance P, Flag™ peptide (Hopp et al., Biotechnology 6:1204-10, 1988), streptavidin binding peptide, or other antigenic epitope or binding domain. See, in general, Ford et al., Protein Expression and Purification 2: 95-107, 1991. DNAs encoding affinity tags are available from commercial suppliers (e.g., Pharmacia Biotech, Piscataway, N.J.).

The term “allelic variant” is used herein to denote any of two or more alternative forms of a gene occupying the same chromosomal locus. Allelic variation arises naturally through mutation, and may result in phenotypic polymorphism within populations. Gene mutations can be silent (no change in the encoded polypeptide) or may encode polypeptides having altered amino acid sequence. The term allelic variant is also used herein to denote a protein encoded by an allelic variant of a gene.

The terms “amino-terminal” and “carboxyl-terminal” are used herein to denote positions within polypeptides. Where the context allows, these terms are used with reference to a particular sequence or portion of a polypeptide to denote proximity or relative position. For example, a certain sequence positioned carboxyl-terminal to a reference sequence within a polypeptide is located proximal to the carboxyl terminus of the reference sequence, but is not necessarily at the carboxyl terminus of the complete polypeptide.

The term “complement/anti-complement pair” denotes non-identical moieties that form a non-covalently associated, stable pair under appropriate conditions. For instance, biotin and avidin (or streptavidin) are prototypical members of a complement/anti-complement pair. Other exemplary complement/anti-complement pairs include receptor/ligand pairs, antibody/antigen (or hapten or epitope) pairs, sense/antisense polynucleotide pairs, and the like. Where subsequent dissociation of the complement/anti-complement pair is desirable, the complement/anti-complement pair preferably has a binding affinity of <10⁹ M⁻¹.

The term “complements of a polynucleotide molecule” denotes a polynucleotide molecule having a complementary base sequence and reverse orientation as compared to a reference sequence. For example, the sequence 5′ ATGCACGGG 3′ is complementary to 5′CCCGTGCAT 3′.

The term “contig” denotes a polynucleotide that has a contiguous stretch of identical or complementary sequence to another polynucleotide. Contiguous sequences are said to “overlap” a given stretch of polynucleotide sequence either in their entirety or along a partial stretch of the polynucleotide. For example, representative contigs to the polynucleotide sequence 5′-ATGGCTTAGCTT-3′ (SEQ ID NO:18) are 5′-TAGCTTgagtct-3′ (SEQ ID NO:19) and 3′-gtcgacTACCGA-5′ (SEQ ID NO:20).

The term “degenerate nucleotide sequence” denotes a sequence of nucleotides that includes one or more degenerate codons (as compared to a reference polynucleotide molecule that encodes a polypeptide). Degenerate codons contain different triplets of nucleotides, but encode the same amino acid residue (i.e., GAU and GAC triplets each encode Asp).

The term “expression vector” is used to denote a DNA molecule, linear or circular, that comprises a segment encoding a polypeptide of interest operably linked to additional segments that provide for its transcription. Such additional segments include promoter and terminator sequences, and may also include one or more origins of replication, one or more selectable markers, an enhancer, a polyadenylation signal, etc. Expression vectors are generally derived from plasmid or viral DNA, or may contain elements of both.

The term “isolated”, when applied to a polynucleotide, denotes that the polynucleotide has been removed from its natural genetic milieu and is thus free of other extraneous or unwanted coding sequences, and is in a form suitable for use within genetically engineered protein production systems. Such isolated molecules are those that are separated from their natural environment and include cDNA and genomic clones. Isolated DNA molecules of the present invention are free of other genes with which they are ordinarily associated, but may include naturally occurring 5′ and 3′ untranslated regions such as promoters and terminators. The identification of associated regions will be evident to one of ordinary skill in the art (see for example, Dynan and Tijan, Nature 316:774-78, 1985).

An “isolated” polypeptide or protein is a polypeptide or protein that is found in a condition other than its native environment, such as apart from blood and animal tissue. In a preferred form, the isolated polypeptide is substantially free of other polypeptides, particularly other polypeptides of animal origin. It is preferred to provide the polypeptides in a highly purified form, i.e. greater than 95% pure, more preferably greater than 99% pure. When used in this context, the term “isolated” does not exclude the presence of the same polypeptide in alternative physical forms, such as dimers or alternatively glycosylated or derivatized forms.

The term “operably linked”, when referring to DNA segments, indicates that the segments are arranged so that they function in concert for their intended purposes, e.g., transcription initiates in the promoter and proceeds through the coding segment to the terminator.

The term “ortholog” denotes a polypeptide or protein obtained from one species that is the functional counterpart of a polypeptide or protein from a different species. Sequence differences among orthologs are the result of speciation.

“Paralogs” are distinct but structurally related proteins made by an organism. Paralogs are believed to arise through gene duplication. For example, α-globin, β-globin, and myoglobin are paralogs of each other.

A “polynucleotide” is a single- or double-stranded polymer of deoxyribonucleotide or ribonucleotide bases read from the 5′ to the 3′ end. Polynucleotides include RNA and DNA, and may be isolated from natural sources, synthesized in vitro, or prepared from a combination of natural and synthetic molecules. Sizes of polynucleotides are expressed as base pairs (abbreviated “bp”), nucleotides (“nt”), or kilobases (“kb”). Where the context allows, the latter two terms may describe polynucleotides that are single-stranded or double-stranded. When the term is applied to double-stranded molecules it is used to denote overall length and will be understood to be equivalent to the term “base pairs”. It will be recognized by those skilled in the art that the two strands of a double-stranded polynucleotide may differ slightly in length and that the ends thereof may be staggered as a result of enzymatic cleavage; thus all nucleotides within a double-stranded polynucleotide molecule may not be paired.

A “polypeptide” is a polymer of amino acid residues joined by peptide bonds, whether produced naturally or synthetically. Polypeptides of less than about 10 amino acid residues are commonly referred to as “peptides”.

The term “promoter” is used herein for its art-recognized meaning to denote a portion of a gene containing DNA sequences that provide for the binding of RNA polymerase and initiation of transcription. Promoter sequences are commonly, but not always, found in the 5′ non-coding regions of genes.

A “protein” is a macromolecule comprising one or more polypeptide chains. A protein may also comprise non-peptidic components, such as carbohydrate groups. Carbohydrates and other non-peptidic substituents may be added to a protein by the cell in which the protein is produced, and will vary with the type of cell. Proteins are defined herein in terms of their amino acid backbone structures; substituents such as carbohydrate groups are generally not specified, but may be present nonetheless.

The term “receptor” denotes a cell-associated protein that binds to a bioactive molecule (i.e., a ligand) and mediates the effect of the ligand on the cell. Membrane-bound receptors are characterized by a multi-peptide structure comprising an extracellular ligand-binding domain and an intracellular effector domain that is typically involved in signal transduction. Binding of ligand to receptor results in a conformational change in the receptor that causes an interaction between the effector domain and other molecule(s) in the cell. This interaction in turn leads to an alteration in the metabolism of the cell. Metabolic events that are linked to receptor-ligand interactions include gene transcription, phosphorylation, dephosphorylation, increases in cyclic AMP production, mobilization of cellular calcium, mobilization of membrane lipids, cell adhesion, hydrolysis of inositol lipids and hydrolysis of phospholipids. In general, receptors can be membrane bound, cytosolic or nuclear; monomeric (e.g., thyroid stimulating hormone receptor, beta-adrenergic receptor) or multimeric (e.g., PDGF receptor, growth hormone receptor, IL-3 receptor, GM-CSF receptor, G-CSF receptor, erythropoietin receptor and IL-6 receptor).

The term “secretory signal sequence” denotes a DNA sequence that encodes a polypeptide (a “secretory peptide”) that, as a component of a larger polypeptide, directs the larger polypeptide through a secretory pathway of a cell in which it is synthesized. The larger polypeptide is commonly cleaved to remove the secretory peptide during transit through the secretory pathway.

A “soluble receptor” is a receptor polypeptide that is not bound to a cell membrane. Soluble receptors are most commonly ligand-binding receptor polypeptides that lack transmembrane and cytoplasmic domains. Soluble receptors can comprise additional amino acid residues, such as affinity tags that provide for purification of the polypeptide or provide sites for attachment of the polypeptide to a substrate, or immunoglobulin constant region sequences. Many cell-surface receptors have naturally occurring, soluble counterparts that are produced by proteolysis. Soluble receptor polypeptides are said to be substantially free of transmembrane and intracellular polypeptide segments when they lack sufficient portions of these segments to provide membrane anchoring or signal transduction, respectively.

The term “splice variant” is used herein to denote alternative forms of RNA transcribed from a gene. Splice variation arises naturally through use of alternative splicing sites within a transcribed RNA molecule, or less commonly between separately transcribed RNA molecules, and may result in several mRNAs transcribed from the same gene. Splice variants may encode polypeptides having altered amino acid sequence. The term splice variant is also used herein to denote a protein encoded by a splice variant of an mRNA transcribed from a gene.

Molecular weights and lengths of polymers determined by imprecise analytical methods (e.g., gel electrophoresis) will be understood to be approximate values. When such a value is expressed as “about” X or “approximately” X, the stated value of X will be understood to be accurate to ±10%.

All references cited herein are incorporated by reference in their entirety.

The present invention provides novel methods of using IL-31RA antagonists in detection, diagnosis, and treatment of diseases, in particular, diseases that have a high correlation of cutaneous lymphocyte antigen (CLA). The present invention is based in part upon the discovery that a previously identified cytokine, IL-31 is expressed by skin-homing T cells, but not gut-homing T cells.

IL-31 is a recently discovered protein having the structure of a four-helical-bundle cytokine. This cytokine was previously identified as IL-31 and is fully described in U.S. patent application Ser. No. 10/352,554, filed Jan. 21, 2003. See published U.S. Patent Application No. 2003-0224487, and PCT application WO 03/060090, all herein incorporated by reference. See also, Dillon, et al., Nature Immunol. 5:752-760, 2004. IL-31 is a ligand with high specificity for the receptor IL-31RA and at least one additional subunit comprising OncostatinM receptor beta (OSMRbeta). The native polynucleotide and polypeptide sequences for human IL-31 are shown in SEQ ID NOs:1 and 2, respectively. The native polynucleotide and polypeptide sequences for mouse IL-31 are shown in SEQ ID NOs:3 and 4, respectively.

As used herein the term, IL-31 also means and is interchangeably referred to as Zcytor17lig, and IL-31RA also means and is interchangeably referred to as Zcytor17, as used in U.S. patent publication number 20030224487 (herein incorporated by reference), as shown above. The heterodimeric receptor for IL-31 was also described in 20030224487 as comprising zcytor17 (HUGO name, IL-31RA) and with at least one additional subunit comprising OncostatinM receptor beta (OSMRbeta).

The native polynucleotide and polypeptide sequences for the “long” form of IL-31RA are shown in SEQ ID NOs:5 and 6, respectively. The native polynucleotide and polypeptide sequences for the “short” form of IL-31RA are shown in SEQ ID NOs:7 and 8, respectively. Additionally, truncated forms of IL-31RA polypeptide appear to be naturally expressed. Both forms encode soluble IL-31RA receptors. The “long” soluble IL-31RA polynucleotide and polypeptide sequences are shown in SEQ ID NOs:9 and 10, respectively. The “short” soluble IL-31RA polynucleotide and polypeptide sequences are shown in SEQ ID NOs:11 and 12, respectively. The native polynucleotide and polypeptide sequences for mouse IL-31RA are shown in SEQ ID NOs:13 and 14, respectively. The native polynucleotide and polypeptide sequences for human OSMRbeta are shown in SEQ ID NOs:15 and 16, respectively. See PCT applications WO 02/00721 and WO 04/003140, both of which are incorporated by reference.

The secretory signal sequence of IL-31 is comprised of amino acid residues 1 (Met) to 23 (Ala), and the mature polypeptide is comprised of amino acid residues 24 (Ser) to 164 (Thr) as shown in SEQ ID NO:2. Further N-terminal sequencing analysis of purified IL-31 from 293T cells showed an N-terminus at residue 27 (Leu) as shown in SEQ ID NO:2, with the mature polypeptide comprised of amino acid residues 27 (Leu) to 164 (Thr) as shown in SEQ ID NO:2.

Cytokine receptor subunits are characterized by a multi-domain structure comprising an extracellular domain, a transmembrane domain that anchors the polypeptide in the cell membrane, and an intracellular domain. The extracellular domain may be a ligand-binding domain, and the intracellular domain may be an effector domain involved in signal transduction, although ligand-binding and effector functions may reside on separate subunits of a multimeric receptor. The domains and structural features of the IL-31RA polypeptides (zcytor17) are further described below.

Analysis of the IL-31RA polypeptide encoded by the DNA sequence of SEQ ID NO:5 revealed an open reading frame encoding 732 amino acids (SEQ ID NO:6) comprising a predicted secretory signal peptide of 19 amino acid residues (residue 1 (Met) to residue 19 (Ala) of SEQ ID NO:6), and a mature polypeptide of 713 amino acids (residue 20 (Ala) to residue 732 (Val) of SEQ ID NO:6). Analysis of the IL-31RA polypeptide encoded by the DNA sequence of SEQ ID NO:7 revealed an open reading frame encoding 662 amino acids (SEQ ID NO:8) comprising a predicted secretory signal peptide of 32 amino acid residues (residue 1 (Met) to residue 32 (Ala) of SEQ ID NO:8), and a mature polypeptide of 630 amino acids (residue 33 (Ala) to residue 662 (Ile) of SEQ ID NO:8). In addition to the WSXWS motif (SEQ ID NO:17) (corresponding to residues 211 to 215 of SEQ ID NO:6; and residues 224 to 228 of SEQ ID NO:8), the receptor comprises an extracellular domain (residues 20 (Ala) to 519 (Glu) of SEQ ID NO:6; residues 33 (Ala) to 532 (Glu) of SEQ ID NO:8) which includes a cytokine-binding domain of approximately 200 amino acid residues (residues 20 (Ala) to 227 (Pro) of SEQ ID NO:6; residues 33 (Ala) to 240 (Pro) of SEQ ID NO:8); a domain linker (residues 122 (Thr) to 125 (Pro) of SEQ ID NO:6; residues 135 (Thr) to 138 (Pro) of SEQ ID NO:8); a penultimate strand region (residues 194 (Phe) to 202 (Arg) of SEQ ID NO:6; residues 207 (Phe) to 215 (Arg) of SEQ ID NO:8); a fibronectin type III domain (residues 228 (Cys) to 519 (Glu) of SEQ ID NO:6; residues 241 (Cys) to 532 (Glu) of SEQ ID NO:8); a transmembrane domain (residues 520 (Ile) to 543 (Leu) of SEQ ID NO:6; residues 533 (Ile) to 556 (Leu) of SEQ ID NO:8); complete intracellular signaling domain (residues 544 (Lys) to 732 (Val) of SEQ ID NO:6; and residues 557 (Lys) to 662 (Ile) of SEQ ID NO:8) which contains a “Box I” signaling site (residues 554 (Trp) to 560 (Pro) of SEQ ID NO:6; residues 567 (Trp) to 573 (Pro) of SEQ ID NO:8), and a “Box II” signaling site (residues 617 (Gln) to 620 (Phe) of SEQ ID NO:6; residues 630 (Gln) to 633 (Phe) of SEQ ID NO:8). Those skilled in the art will recognize that these domain boundaries are approximate, and are based on alignments with known proteins and predictions of protein folding. In addition to these domains, conserved receptor features in the encoded receptor include (as shown in SEQ ID NO:6) a conserved Cys residue at position 30 (position 43 as shown in SEQ ID NO:8), CXW motif (wherein X is any amino acid) at positions 40-42 of SEQ ID NO:6 (positions 53-55 as shown in SEQ ID NO:8), Trp residue at position 170 of SEQ ID NO:6 (position 183 as shown in SEQ ID NO:8), and a conserved Arg residue at position 202 of SEQ ID NO:6 (position 215 as shown in SEQ ID NO:8). The corresponding polynucleotides encoding the IL-31RA polypeptide regions, domains, motifs, residues and sequences described above are as shown in SEQ ID NOs:5 and 7.

Moreover, truncated forms of the IL-31RA polypeptide appear to be naturally expressed. Both forms encode soluble zcytor17 receptors. A polynucleotide encoding a “long-form” of the soluble zcytor17 receptor, truncated within the fibronectin type III domain, is shown in SEQ ID NO:9 and the corresponding polypeptide is shown in SEQ ID NO:10. This truncated form encodes residues 1 (Met) through 324 (Lys) of SEQ ID NO:6, and thus comprises an intact signal sequence, WSXWS (SEQ ID NO:17) motif, linker, cytokine binding domain, penultimate strand, and conserved, Cys, CXW motif, Trp and Arg residues as described above. A polynucleotide encoding a “short-form” of the soluble IL-31RA receptor, truncated at the end of the cytokine binding domain is shown in SEQ ID NO:11 and the corresponding polypeptide is shown in SEQ ID NO:12. This truncated form encodes a 239 residue polypeptide that is identical to residues 1 (Met) through 225 (Glu) of SEQ ID NO:6 and then diverges, and thus comprises an intact signal sequence, WSXWS (SEQ ID NO:17) motif, linker, cytokine binding domain, penultimate strand, and conserved, Cys, CXW motif, Trp and Arg residues as described above.

Both skin-homing T cells and epidermal keratinocytes have been implicated in the pathology of skin diseases in humans. As shown herein, IL-31 mRNA and protein expression is restricted to the skin-homing CLA+ T cell population in both atopic dermatitis (AD) patients and normal individuals, while analysis of the receptor for IL-31, IL-31RA, by immunohistochemistry (IHC) suggests slightly higher levels of IL-31RA expression on skin keratinocytes in skin biopsies from acute and chronic AD sufferers compared to normal individuals.

When over-expressed in mice, IL-31 results in pruritus and the development of skin dermatitis resembling human atopic dermatitis (AD). Immunohistochemistry (IHC) studies shown herein show that IL-31RA protein was expressed by skin keratinocytes and infiltrating macrophages in skin biopsies from AD patients. Comparisons between AD patients and normal individuals suggested that IL-31RA was expressed at higher levels on epidermal keratinocytes in the AD samples. Skin cell infiltrates, which were present at greater numbers in skin of AD patients compared to normal individuals, expressed IL-31 mRNA. Histomorphometric analysis of these cells suggested a lymphocytic lineage with the majority of cells staining positive for cutaneous lymphocyte antigen (CLA) and CD3, demonstrating that skin-homing T cells in skin express IL-31 mRNA. Upon analysis of peripheral blood T cells for IL-31, IL-31 mRNA and protein expression is largely restricted to CD45RO+ CLA+ skin-homing T cells in AD and normal volunteers. Moreover, circulating CLA+ T cells from AD patients are capable of producing higher levels of IL-31 compared to CLA+ T cells from normal individuals, though there is large variability between patient samples. These results provide strong evidence that IL-31 expression is associated with atopic dermatitis and may contribute to the development of AD skin inflammation and pruritus.

As shown herein, IL-31 is produced both locally in the skin and by skin infiltrating cells. Local production of cytokines in tissues by T cells is thought to be a key mechanism for disease pathogenesis in AD and increased numbers of T cells both in circulation and in skin is thought to correlate with disease.

Although both AD patients and normal controls have circulating CLA+ T cells that express IL-31 upon activation, CLA+ T cells from AD patients are reported to exist in a more activated state compared to cells from normal individuals. See Akdis M, J Immunol., 159:4611-4619, 1997. Consequently, the threshold of stimulation required for the production of IL-31 by CLA+ T cells may differ between dermatitis patients and control subjects. As shown herein, circulating CLA+ T cells from AD patients after 24 hours of stimulation with sub-optimal concentrations of anti-CD3 in the absence of anti-CD28 have the capacity to produce higher levels of IL-31 compared to cells from normal individuals. Due to the variability in IL-31 levels produced by CLA+ T cells from individual AD patients, there was no significant difference in the average IL-31 production from circulating CLA+ T cells of AD and normal individuals. Nevertheless, since more CLA+ T cells are localized in skin of AD patients, as compared to normal individuals, there is an increased potential for IL-31 activity in the AD skin micro-environment.

Example 1 demonstrates that circulating CLA+ T cells from some AD patients produce higher levels of IL-31 compared to cells from normal individuals. The detection of IL-31 in patients of such a subpopulation using the bioassay provided herein, or with any assay that detects IL-31 produced by circulating T cells in the blood, may be useful to determine if an IL-31 antagonist will be useful as treatment for diseases wherein the presence of IL-31 causes inflammation.

A cell line that is dependent on the OSMRbeta and IL-31RA linked pathway for survival and growth in the absence of other growth factors can be used to measure the activity of IL-31. Such growth factor-dependent cell lines include BaF3, FDC-P1, and MO7e. For information on the BaF3 cell line, see Palacios and Steinmetz, (Cell, 41:727-734, 1985) and Mathey-Prevot et al., (Mol. Cell. Biol., 6:4133-4135, 1986). For information on the FDC-P1 cell line, see Hapel et al. (Blood, 64:786-790, 1984). For information on the MO7e cell line, see Kiss et al., (Leukemia, 7:235-240, 1993).

The amino acid sequence for the OSMRbeta, and IL-31RA receptors indicated that the encoded receptors belonged to the Class I cytokine receptor subfamily that includes, but is not limited to, the receptors for IL-2, IL-4, IL-7, Lif, IL-12, IL-15, EPO, TPO, GM-CSF and G-CSF (for a review see, Cosman, “The Hematopoietin Receptor Superfamily” in Cytokine 5(2): 95-106, 1993). The IL-31RA receptor is fully described in PCT Patent Application No. US01/20484 (WIPO publication No. WO 02/00721). Analysis of the tissue distribution of the mRNA of the IL-31RA receptor revealed expression in activated CD4+ and CD8+ T-cell subsets, CD14+ monocytes, and weaker expression in CD19+ B-cells. Moreover, the mRNA was present in both resting or activated monocytic cell lines THP-1 (ATCC No. TIB-202), U937 (ATCC No. CRL-1593.2) and HL60 (ATCC No. CCL-240).

Antigenic epitope-bearing peptides and polypeptides preferably contain at least four to ten amino acids, at least ten to fourteen amino acids, or about fourteen to about thirty amino acids of the extracellular domains of SEQ ID NO:6 or SEQ ID NO:8. Such epitope-bearing peptides and polypeptides can be produced by fragmenting the extracellular domain of IL-31RA polypeptide, or by chemical peptide synthesis, as described herein. Moreover, epitopes can be selected by phage display of random peptide libraries (see, for example, Lane and Stephen, Curr. Opin. Immunol. 5:268 (1993); and Cortese et al., Curr. Opin. Biotechnol. 7:616 (1996)). Standard methods for identifying epitopes and producing antibodies from small peptides that comprise an epitope are described, for example, by Mole, “Epitope Mapping,” in Methods in Molecular Biology, Vol. 10, Manson (ed.), pages 105-116 (The Humana Press, Inc. 1992); Price, “Production and Characterization of Synthetic Peptide-Derived Antibodies,” in Monoclonal Antibodies: Production, Engineering, and Clinical Application, Ritter and Ladyman (eds.), pages 60-84 (Cambridge University Press 1995), and Coligan et al. (eds.), Current Protocols in Immunology, pages 9.3.1-9.3.5 and pages 9.4.1-9.4.11 (John Wiley & Sons 1997).

The IL-31RA polypeptides of the present invention, including full-length polypeptides, functional fragments, and fusion polypeptides, can be produced, purified and refolded by methods well-known in the art and as described in PCT applications WO 02/00721 and WO 04/003140. It is preferred to purify the polypeptides of the present invention to ≧80% purity, more preferably to ≧90% purity, even more preferably ≧95% purity, and particularly preferred is a pharmaceutically pure state, that is greater than 99.9% pure with respect to contaminating macromolecules, particularly other proteins and nucleic acids, and free of infectious and pyrogenic agents. Preferably, a purified polypeptide is substantially free of other polypeptides, particularly other polypeptides of animal origin.

The present invention provides methods for using IL-31RA antagonists, including anti-IL-31RA antibodies and fragments, soluble IL-31RA receptors, and soluble IL-31RA/OSMRbeta receptors for reducing, inhibiting, or preventing inflammation in cell microenvironments where one or more cells in the microenvironment is/are T cells that are positive for the cutaneous lymphocyte antigen.

Antibodies from an immune response generated by inoculation of an animal with IL-31RA antigens, e.g., extracellular domain of SEQ ID NO:6 or a portion thereof, such as ligand binding domain) can be isolated and purified are known in the art and are described herein. Methods for preparing and isolating polyclonal and monoclonal antibodies are well known in the art. See, for example, Current Protocols in Immunology, Cooligan, et al. (eds.), National Institutes of Health, John Wiley and Sons, Inc., 1995; Sambrook et al., Molecular Cloning: A Laboratory Manual, Second Edition, Cold Spring Harbor, N.Y., 1989; and Hurrell, J. G. R., Ed., Monoclonal Hybridoma Antibodies: Techniques and Applications, CRC Press, Inc., Boca Raton, Fla., 1982.

As would be evident to one of ordinary skill in the art, polyclonal antibodies can be generated from inoculating a variety of warm-blooded animals such as horses, cows, goats, sheep, dogs, chickens, rabbits, mice, and rats with a IL-31RA polypeptide or a fragment thereof. The immunogenicity of an IL-31RA polypeptide may be increased through the use of an adjuvant, such as alum (aluminum hydroxide) or Freund's complete or incomplete adjuvant. Polypeptides useful for immunization also include fusion polypeptides, such as fusions of IL-31RA or a portion thereof with an immunoglobulin polypeptide or with maltose binding protein. The polypeptide immunogen may be a full-length molecule or a portion thereof. If the polypeptide portion is “hapten-like”, such portion may be advantageously joined or linked to a macromolecular carrier (such as keyhole limpet hemocyanin (KLH), bovine serum albumin (BSA) or tetanus toxoid) for immunization.

As used herein, the term “antibodies” includes polyclonal antibodies, affinity-purified polyclonal antibodies, monoclonal antibodies, and antigen-binding fragments, such as Fab fragment, Fab′ fragment, F(ab′)₂ fragment, single chain Fv (scFv) proteolytic fragments. Genetically engineered intact antibodies or fragments, such as chimeric antibodies, Fv fragments, single chain antibodies and the like, as well as synthetic antigen-binding peptides and polypeptides, are also included. Non-human antibodies may be humanized by grafting non-human CDRs onto human framework and constant regions, or by incorporating the entire non-human variable domains (optionally “cloaking” them with a human-like surface by replacement of exposed residues, wherein the result is a “veneered” antibody). In some instances, humanized antibodies may retain non-human residues within the human variable region framework domains to enhance proper binding characteristics. Through humanizing antibodies, biological half-life may be increased, and the potential for adverse immune reactions upon administration to humans is reduced. Moreover, human antibodies can be produced in transgenic, non-human animals that have been engineered to contain human immunoglobulin genes as disclosed in WIPO Publication No. WO 98/24893. It is preferred that the endogenous immunoglobulin genes in these animals be inactivated or eliminated, such as by homologous recombination.

Antibodies are considered to be specifically binding if: 1) they exhibit a threshold level of binding activity, and 2) they do not significantly cross-react with related polypeptide molecules. A threshold level of binding is determined if anti-IL-31RA antibodies herein bind to an IL-31RA polypeptide, peptide or epitope with an affinity at least 10-fold greater than the binding affinity to control (non-IL-31RA) polypeptide. It is preferred that the antibodies exhibit a binding affinity (Ka) of 10⁶ M-1 or greater, preferably 10⁷ M-1 or greater, more preferably 108 M-1 or greater, and most preferably 10⁹ M-1 or greater. The binding affinity of an antibody can be readily determined by one of ordinary skill in the art, for example, by Scatchard analysis (Scatchard, G., Ann. NY Acad. Sci. 51: 660-672, 1949).

The present invention provides a method of treating a patient suffering from a skin disorder, the method comprises administering a therapeutically effective amount of an anti-IL-31RA antibody or fragment to the patient, wherein the anti-IL-31RA antibody or fragment binds with amino acid residues 20-519 of SEQ ID NO:6 or portion thereof, or amino acid residues 33-532 of SEQ ID NO:8 or portion thereof, and wherein the anti-IL-31RA antibody or fragment prevents, inhibits the progression of, delays the onset of, reduces the severity of, and/or inhibits at least one of the conditions or symptoms of the skin disorder selected from the group consisting of Atopic Dermititis, Contact dermatitis, Drug induced delayed type cutaneous allergic reactions, Toxic epidermal necrolysis, Cutaneous T cell Lymphoma, Bullous pemphigoid, Alopecia aereata, Vitiligo, Acne Rosacea, Prurigo nodularis, Scleroderma, and Herpes simplex virus. The anti-IL-31RA antibody may optionally be a polyclonal antibody or a neutralizing monoclonal antibody (the present invention also provides for a hybridoma for producing the neutralizing IL-31RA monoclonal antibody). The anti-IL-31RA antibody fragment may optionally be a Fab fragment, a Fab′ fragment, a F(ab′)2 fragment, single chain Fv (scFV), dual specific antibody, domain antibody, or bispecific antibody. The anti-IL-31RA antibody or fragment may bind with amino acid residues 20-277 of SEQ ID NO:6 or 33-240 of SEQ ID NO:8. The anti-IL-31RA antibody or fragment may bind with about 4-10 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8. The anti-IL-31RA antibody or fragment may bind with about 10-14 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8. The anti-IL-31RA antibody or fragment may bind with about 14-30 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8. The anti-IL-31 antibody or fragment may be further conjugated to a polyethylene glycol or to human serum albumin.

The present invention also provides for a method of treating a patient suffering from a skin disorder, the method comprises administering a therapeutically effective amount of a soluble IL-31RA receptor to the patient, wherein the soluble IL-31RA receptor binds with an IL-31 polypeptide consisting of amino acid residues 1-164 SEQ ID NO:2, and wherein the soluble IL-31RA receptor prevents, inhibits the progression of, delays the onset of, reduces the severity of, and/or inhibits at least one of the conditions or symptoms of the skin disorder selected from the group consisting of Atopic Dermititis, Contact dermatitis, Drug induced delayed type cutaneous allergic reactions, Toxic epidermal necrolysis, Cutaneous T cell Lymphoma, Bullous pemphigoid, Alopecia aereata, Vitiligo, Acne Rosacea, Prurigo nodularis, Scleroderma, and Herpes simplex virus. The soluble IL-31RA receptor may comprise amino acid residues 20-519 of SEQ ID NO:6 or 33-240 of SEQ ID NO:8, amino acid residues 1-324 of SEQ ID NO:10, or amino acid residues 1-239 of SEQ ID NO:12. The soluble IL-31RA receptor may be further conjugated to the Fc region of the various immunoglobulins (IgG, IgA, IgD, IgM or IgE). Optionally, the soluble IL-31RA receptor may be an IL-31RA homodimer or an IL-31RA/OSMRbeta heterodimer. The soluble IL-31RA receptor may bind with an IL-31 polypeptide comprising, consisting essentially of, consisting of amino acid residues 24-164 of SEQ ID NO:2 or 27-164 of SEQ ID NO:2. The soluble IL-31RA receptor may be further conjugated to a polyethylene glycol or to human serum albumin.

The present invention also provides isolated IL-31RA encoding nucleic acid molecules that can hybridize under stringent conditions to nucleic acid molecules having the nucleotide sequence of nucleotides 58-1557 of SEQ ID NO:5 or nucleotides 97-1596 SEQ ID NO:7, or to nucleic acid molecules having a nucleotide sequence complementary to nucleotides 58-1557 of SEQ ID NO:5 or to nucleotides 97-1596 SEQ ID NO:7. In general, stringent conditions are selected to be about 5*C lower than the thermal melting point (Tm) for the specific sequence at a defined ionic strength and pH. The Tm is the temperature (under defined ionic strength and pH) at which 50% of the target sequence hybridizes to a perfectly matched probe.

A pair of nucleic acid molecules, such as DNA-DNA, RNA-RNA and DNA-RNA, can hybridize if the nucleotide sequences have some degree of complementarity. Hybrids can tolerate mismatched base pairs in the double helix, but the stability of the hybrid is influenced by the degree of mismatch. The Tm of the mismatched hybrid decreases by 1° C. for every 1-1.5% base pair mismatch. Varying the stringency of the hybridization conditions allows control over the degree of mismatch that will be present in the hybrid. The degree of stringency increases as the hybridization temperature increases and the ionic strength of the hybridization buffer decreases.

It is well within the abilities of one skilled in the art to adapt these conditions for use with a particular polynucleotide hybrid. The Tm for a specific target sequence is the temperature (under defined conditions) at which 50% of the target sequence will hybridize to a perfectly matched probe sequence. Those conditions which influence the Tm include, the size and base pair content of the polynucleotide probe, the ionic strength of the hybridization solution, and the presence of destabilizing agents in the hybridization solution. Numerous equations for calculating Tm are known in the art, and are specific for DNA, RNA and DNA-RNA hybrids and polynucleotide probe sequences of varying length (see, for example, Sambrook et al., Molecular Cloning: A Laboratory Manual, Second Edition (Cold Spring Harbor Press 1989); Ausubel et al., (eds.), Current Protocols in Molecular Biology (John Wiley and Sons, Inc. 1987); Berger and Kimmel (eds.), Guide to Molecular Cloning Techniques, (Academic Press, Inc. 1987); and Wetmur, Crit. Rev. Biochem. Mol. Biol. 26:227 (1990)). Sequence analysis software such as OLIGO 6.0 (LSR; Long Lake, Minn.) and Primer Premier 4.0 (Premier Biosoft International; Palo Alto, Calif.), as well as sites on the Internet, are available tools for analyzing a given sequence and calculating Tm based on user defined criteria. Such programs can also analyze a given sequence under defined conditions and identify suitable probe sequences. Typically, hybridization of longer polynucleotide sequences, >50 base pairs, is performed at temperatures of about 20-25° C. below the calculated Tm. For smaller probes, <50 base pairs, hybridization is typically carried out at the Tm or 5-10° C. below the calculated Tm. This allows for the maximum rate of hybridization for DNA-DNA and DNA-RNA hybrids.

Following hybridization, the nucleic acid molecules can be washed to remove non-hybridized nucleic acid molecules under stringent conditions, or under highly stringent conditions. Typical stringent washing conditions include washing in a solution of 0.5×-2×SSC with 0.1% sodium dodecyl sulfate (SDS) at 55-65° C. That is, nucleic acid molecules encoding a variant IL-31RA polypeptide hybridize with a nucleic acid molecule having the nucleotide sequence of nucleotides 58-1557 of SEQ ID NO:5 (or its complement) or nucleotides 97-1596 SEQ ID NO:7 (or its complement) under stringent washing conditions, in which the wash stringency is equivalent to 0.5×-2×SSC with 0.1% SDS at 55-65° C., including 0.5×SSC with 0.1% SDS at 55° C., or 2×SSC with 0.1% SDS at 65° C. One of skill in the art can readily devise equivalent conditions, for example, by substituting SSPE for SSC in the wash solution.

Typical highly stringent washing conditions include washing in a solution of 0.1×-0.2×SSC with 0.1% sodium dodecyl sulfate (SDS) at 50-65° C. In other words, nucleic acid molecules encoding a variant IL-31RA polypeptide hybridize with a nucleic acid molecule having the nucleotide sequence of SEQ ID NO:1 (or its complement) under highly stringent washing conditions, in which the wash stringency is equivalent to 0.1×-0.2×SSC with 0.1% SDS at 50-65° C., including 0.1×SSC with 0.1% SDS at 50° C., or 0.2×SSC with 0.1% SDS at 65° C.

The present invention also provides isolated IL-31RA polypeptides that have a substantially similar sequence identity to the polypeptides having amino acid residues 20-519 of SEQ ID NO:6 and/or amino acid residues 33-532 of SEQ ID NO:8, or their orthologs. The term “substantially similar sequence identity” is used herein to denote polypeptides comprising at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99-0.5%, or greater than 99.5% sequence identity to the sequences shown in amino acid residues 20-519 of SEQ ID NO:6 and/or amino acid residues 33-532 of SEQ ID NO:8, or their orthologs. The present invention further includes nucleic acid molecules that encode such polypeptides. Methods for determining percent identity are described PCT publications WO 02/00721 (incorporated by reference) and 04/003140 (incorporated by reference).

The present invention provides a method of treating a patient suffering from a skin disorder, the method comprises administering a therapeutically effective amount of an anti-IL-31RA antibody or fragment to the patient, wherein the anti-IL-31RA antibody or fragment binds with an amino acid sequence having at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, or great than 99.5% sequence identity with amino acid residues 20-519 of SEQ ID NO:6 or portion thereof, or amino acid residues 33-532 of SEQ ID NO:8 or portion thereof, and wherein the anti-IL-31RA antibody or fragment prevents, inhibits the progression of, delays the onset of, reduces the severity of, and/or inhibits at least one of the conditions or symptoms of the skin disorder selected from the group consisting of Atopic Dermititis, Contact dermatitis, Drug induced delayed type cutaneous allergic reactions, Toxic epidermal necrolysis, Cutaneous T cell Lymphoma, Bullous pemphigoid, Alopecia aereata, Vitiligo, Acne Rosacea, Prurigo nodularis, Scleroderma, and Herpes simplex virus. The anti-IL-31RA antibody may optionally be a polyclonal antibody or a neutralizing monoclonal antibody (the present invention also provides for a hybridoma for producing the neutralizing IL-31RA monoclonal antibody). The anti-IL-31RA antibody fragment may optionally be a Fab fragment, a Fab′ fragment, a F(ab′)2 fragment, single chain Fv (scFV), dual specific antibody, domain antibody, or bispecific antibody. The anti-IL-31RA antibody or fragment may bind with amino acid residues 20-277 of SEQ ID NO:6 or 33-240 of SEQ ID NO:8. The anti-IL-31RA antibody or fragment may bind with about 4-10 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8. The anti-IL-31RA antibody or fragment may bind with about 10-14 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8. The anti-IL-31RA antibody or fragment may bind with about 14-30 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8. The anti-IL-31 antibody or fragment may be further conjugated to a polyethylene glycol or to human serum albumin.

The present invention also provides for a method of treating a patient suffering from a skin disorder, the method comprises administering a therapeutically effective amount of a soluble IL-31RA receptor to the patient, wherein the soluble IL-31RA receptor has at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, or great than 99.5% sequence identity with amino acid residues 20-519 of SEQ ID NO:6 or portion thereof, or amino acid residues 33-532 of SEQ ID NO:8, and wherein the soluble IL-31RA receptor binds with an IL-31 polypeptide consisting of amino acid residues 1-164 SEQ ID NO:2, and wherein the soluble IL-31RA receptor prevents, inhibits the progression of, delays the onset of, reduces the severity of, and/or inhibits at least one of the conditions or symptoms of the skin disorder selected from the group consisting of Atopic Dermititis, Contact dermatitis, Drug induced delayed type cutaneous allergic reactions, Toxic epidermal necrolysis, Cutaneous T cell Lymphoma, Bullous pemphigoid, Alopecia aereata, Vitiligo, Acne Rosacea, Prurigo nodularis, Scleroderma, and Herpes simplex virus. The soluble IL-31RA receptor may comprise amino acid residues 20-519 of SEQ ID NO:6 or 33-240 of SEQ ID NO:8, amino acid residues 1-324 of SEQ ID NO:10, or amino acid residues 1-239 of SEQ ID NO:12. The soluble IL-31RA receptor may be further conjugated to the Fc region of the various immunoglobulins (IgG, IgA, IgD, IgM or IgE). Optionally, the soluble IL-31RA receptor may be an IL-31RA homodimer or an IL-31RA/OSMRbeta heterodimer. The soluble IL-31RA receptor may bind with an IL-31 polypeptide comprising, consisting essentially of, consisting of amino acid residues 24-164 of SEQ ID NO:2 or 27-164 of SEQ ID NO:2. The soluble IL-31RA receptor may be further conjugated to a polyethylene glycol or to human serum albumin.

A variety of assays known to those skilled in the art can be utilized to detect antibodies which bind to IL-31RA proteins or polypeptides. Exemplary assays are described in detail in Antibodies: A Laboratory Manual, Harlow and Lane (Eds.), Cold Spring Harbor Laboratory Press, 1988. Representative examples of such assays include: concurrent immunoelectrophoresis, radioimmunoassay, radioimmuno-precipitation, enzyme-linked immunosorbent assay (ELISA), dot blot or Western blot assay, inhibition or competition assay, and sandwich assay. In addition, antibodies can be screened for binding to wild-type versus mutant IL-31RA protein or polypeptide.

Antibodies to IL-31RA may be used for tagging cells that express IL-31RA; for isolating IL-31RA by affinity purification; for diagnostic assays for determining circulating levels of IL-31RA polypeptides; for detecting or quantitating soluble IL-31RA as a marker of underlying pathology or disease; in analytical methods employing FACS; for screening expression libraries; for generating anti-idiotypic antibodies; and as neutralizing antibodies or as antagonists to block IL-31 activity in vitro and in vivo. Suitable direct tags or labels include radionuclides, enzymes, substrates, cofactors, inhibitors, fluorescent markers, chemiluminescent markers, magnetic particles and the like; indirect tags or labels may feature use of biotin-avidin or other complement/anti-complement pairs as intermediates. Antibodies herein may also be directly or indirectly conjugated to drugs, toxins, radionuclides and the like, and these conjugates used for in vivo diagnostic or therapeutic applications. In addition, antibodies to IL-31RA or fragments thereof may be used in vitro to detect denatured IL-31RA or fragments thereof in assays, for example, Western Blots or other assays known in the art.

Suitable detectable molecules may be directly or indirectly attached to the polypeptide or antibody, and include radionuclides, enzymes, substrates, cofactors, inhibitors, fluorescent markers, chemiluminescent markers, magnetic particles and the like. Suitable cytotoxic molecules may be directly or indirectly attached to the polypeptide or antibody, and include bacterial or plant toxins (for instance, diphtheria, toxin, saporin, Pseudomonas exotoxin, ricin, abrin and the like), as well as therapeutic radionuclides, such as iodine-131, rhenium-188 or yttrium-90 (either directly attached to the polypeptide or antibody, or indirectly attached through means of a chelating moiety, for instance). Polypeptides or antibodies may also be conjugated to cytotoxic drugs, such as adriamycin. For indirect attachment of a detectable or cytotoxic molecule, the detectable or cytotoxic molecule can be conjugated with a member of a complementary/anticomplementary pair, where the other member is bound to the polypeptide or antibody portion. For these purposes, biotin/streptavidin is an exemplary complementary/anticomplementary pair.

Polypeptide-toxin fusion proteins or antibody-toxin fusion proteins can be used for targeted cell or tissue inhibition or ablation (for instance, to treat cancer cells or tissues). Alternatively, if the polypeptide has multiple functional domains (i.e., an activation domain or a receptor binding domain, plus a targeting domain), a fusion protein including only the targeting domain may be suitable for directing a detectable molecule, a cytotoxic molecule or a complementary molecule to a cell or tissue type of interest. In instances where the domain only fusion protein includes a complementary molecule, the anti-complementary molecule can be conjugated to a detectable or cytotoxic molecule. Such domain-complementary molecule fusion proteins thus represent a generic targeting carrier or vehicle for cell/tissue-specific delivery of generic anti-complementary-detectable/cytotoxic molecule conjugates.

Both skin-homing T cells and epidermal keratinocytes have been implicated in the pathology of skin diseases in humans. As shown in Example 1 herein, of the T cell subsets, IL-31 mRNA and protein expression is restricted to the skin-homing CLA+ T cell population in humans. As such, an antagonist to IL-31RA, including an antibody or fragment thereof or soluble receptor (IL-31RA and IL-31RA/OSMRbeta soluble receptors) antagonist will be useful in treating, ablating, inhibiting the progression of, and/or reducing the severity of skin and epidermal diseases which have expression of CLA+ T cells. Such diseases include, for example, atopic dermatitis, contact dermatitis, psoriasis, drug-induced allergic reactions, skin-tropic viruses and viral associated pruritis, vitiligo, cutaneous T cell lymphoma, alopecia aerata, acne rosacea, acne vulgaris, prurigo nodularis, and bullous pemphigoid.

Atopic Dermatitis

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disease with a dramatically increasing incidence over the last decades. Clinically AD is characterized by highly pruritic often excoriated plaques and papules that show a chronic relapsing course. The diagnosis of AD is mostly based on major and minor clinical findings. See Hanifin J. M., Arch Dermatol: 135, 1551 (1999). Histopathology reveals spongiosis, hyper and focal parakeratosis in acute lesions, whereas marked epidermal hyperplasia with hyper and parakeratosis, acanthosis/hypergranulosis and perivascular infiltration of the dermis with lymphocytes and abundant mast cells are the hallmarks of chronic lesions.

T cells play a central role in the initiation of local immune responses in tissues and evidence suggests that skin-infiltrating T cells in particular, may play a key role in the initiation and maintenance of disregulated immune responses in the skin. Approximately 90% of infiltrating T cells in cutaneous inflammatory sites express the cutaneous lymphocyte-associated Ag (CLA+) which binds E-selectin, an inducible adhesion molecule on endothelium (reviewed in Santamaria-Babi L. F., et al., Eur J Dermatol: 14, 13, (2004)). A significant increase in circulating CLA+ T cells among AD patients compared with control individuals has been documented (See Teraki Y., et al., Br J Dermatol: 143, 373 (2000)), while others have demonstrated that memory CLA+ T cells from AD patients preferentially respond to allergen extract compared to the CLA− population (See Santamaria-Babi, L. F., et al., J Exp Med: 181, 1935, (1995)). In humans, the pathogenesis of atopic disorders of the skin have been associated with increases in CLA+ T cells that express increased levels of Th-2-type cytokines like IL-5 and IL-13. See Akdis M., et al., Eur J Immunol: 30, 3533 (2000); and Hamid Q., et al., J Allergy Clin Immunol: 98, 225 (1996).

NC/Nga Mice spontaneously develop AD-like lesions that parallel human AD in many aspects, including clinical course and signs, histopathology and immunopathology when housed in non-specified pathogen-free (non-SPF) conditions at around 6-8 weeks of age. In contrast, NC/Nga mice kept under SPF conditions do not develop skin lesions. However, onset of spontaneous skin lesions and scratching behaviour can be synchronized in NC/Nga mice housed in a SPF facility by weekly intradermal injection of crude dust mite antigen. See Matsuoka H., et al., Allergy: 58, 139 (2003). Therefore, the development of AD in NC/Nga is a useful model for the evaluation of novel therapeutics for the treatment of AD.

In addition to the NC/Nga model of spontaneous AD, epicutaneous sensitization of mice using OVA can also be used as a model to induce antigen-dependent epidermal and dermal thickening with a mononuclear infiltrate in skin of sensitized mice. This usually coincides with elevated serum levels of total and specific IgE, however no skin barrier dysfunction or pruritus normally occurs in this model. See Spergel J. M., et al., J Clin Invest, 101: 1614, (1998). This protocol can be modified in order to induce skin barrier disregulation and pruritis by sensitizing DO11.10 OVA TCR transgenic mice with OVA. Increasing the number of antigen-specific T cells that could recognize the sensitizing antigen may increase the level of inflammation in the skin to induce visible scratching behaviour and lichenification/scaling of the skin.

Both the NC/Nga spontaneous AD model and the OVA epicutaneous DO11.10 model are used to investigate expression of IL-31 and IL-31RA in AD. See Example 3.

An IL-31RA neutralizing antagonist could be effective in inhibiting, reducing, minimizing or preventing atopic dermatitis reactions. See Example 3 for an in vivo model for testing the effect of an IL-31 antagonist in an atopic dermatitis model.

Contact Dermatitis

Allergic contact dermatitis is defined as a T cell mediated immune reaction to an antigen that comes into contact with the skin. The CLA+ T cell population is considered to be involved in the initiation of dermatitis since allergen dependent T cell responses are largely confined to the CLA+ population of cells (See Santamaria-Babi, L. F., et al., J Exp Med: 181, 1935, (1995)). Recent data has found that only memory (CD45RO+) CD4+ CLA+ and not CD8+ T cells proliferate and produce both type-1 (IFN-γ) and type-2 (IL-5) cytokines in response to nickel, a common contact hypersensitivity allergen. Furthermore, cells expressing CLA in combination with CD4, CD45RO (memory) or CD69 are increased after nickel-specific stimulation and express the chemokine receptors CXCR3, CCR4, CCR11 but not CCR6. See Moed H., et al., Br J Dermatol: 51, 32, (2004).

In animal models, it has been demonstrated that allergic contact dermatitis is T-cell dependent and that the allergic-responsive T cells migrate to the site of allergen application. See generally: Engeman T. M., et al., J Immunol: 164, 5207, (2000); Ferguson T. A. & Kupper T. S. J. Immunol. 150, 1172, (1993); and Gorbachev A. V. & Fairchild R. L. Crit Rev Immunol: 21, 451 (2001). Since CLA+ T cells produce IL-31 and IL-31 stimulation of skin keratinocytes can induce pro-inflammatory chemokines, IL-31 may be involved in the pathophysiology of contact dermatitis.

An IL-31RA neutralizing antagonist, e.g., antibody or fragment thereof or soluble receptor (IL-31RA and IL-31RA/OSMRbeta soluble receptors), could be effective in inhibiting, reducing, minimizing or preventing contact dermatitis reactions. See Example 2 for an in vivo model for testing the effect of an IL-31 antagonist in a contact dermatitis model.

Drug-Induced Delayed Type Cutaneous Allergic Reactions

Drug-induced delayed type cutaneous allergic reactions are very heterogeneous and may mirror many distinct pathophysiological events. See Brockow K., et al., Allergy, 57, 45 (2002). Immunological mechanisms involved in these reactions have been shown as either antibody or cell mediated. In immediate drug allergy an IgE-mediated antibody reaction can be demonstrated by a positive skin prick and/or intradermal test after 20 min, whereas non-immediate reactions to drugs can occur more than one hour after last drug intake and are often T-cell mediated. Non-immediate T-cell mediated delayed type reactions can occur in patients with adverse drug reactions to penicillins for example. Proliferative T cell responses to penicillins have been shown to be restricted to the memory (CD45RO+) CLA+ subpopulation of T cells from penicillin allergic patients whereas the CD45RO+ CLA− subset shows no proliferative response. See Blanca M., Leyva L., et al., Blood Cells Mol Dis: 31, 75 (2003). Delayed-type hypersensitivity (DTH) reactions can be artificially reproduced in mice, allowing assessment of factors that may be involved in the initiation and perpetuation of the DTH response. An IL-31RA neutralizing antagonist, e.g., antibody or soluble receptor (IL-31RA and IL-31RA/OSMRbeta soluble receptors), could be effective in inhibiting, reducing, minimizing or preventing delayed type hypersensitivity reactions. See Example 4 for an in vivo model of testing the effect of an IL-31 antagonist in a DTH model.

Toxic epidermal necrolysis (TEN) is a very rare but extremely severe drug reaction characterized by widespread apoptosis of epidermis with extensive blisters. Studies have shown that lymphocytes infiltrating the blister are CLA+ T cells and can exhibit cytotoxicity towards epidermal keratinocytes. See Leyva L., et al., J Allergy Clin Immunol: 105, 157 (2000); and Nassif A., Bensussan A., et al., J Allergy Clin Immunol: 114, 1209 2004). A transgenic mouse system, whereby OVA is expressed under the control of the keratin-5 (K5) promoter in the epidermal and hair follicular keratinocytes of mice, has been generated to establish an animal model for TEN. OVA specific CD8+ T cells, when adoptively transferred into K5-OVA mice, undergo activation and proliferation in the skin-draining lymph nodes and target the skin of K5-OVA mice, resulting in development of skin lesions that are reminiscent of TEN. See Azukizawa H., et al., Eur J Immunol: 33, 1879 (2003). An IL-31RA neutralizing antagonist, e.g., antibody or soluble receptor (IL-31RA and IL-31RA/OSMRbeta soluble receptors), could be effective in inhibiting, reducing, minimizing or preventing TEN reactions.

Bullous Pemphigoid

Bullous pemphigoid is a subepidermal disorder which manifests as subepidermal blisters with a dermal infiltrate of neutrophils and eosinophils. Diagnosis is characterized by the presence of antigen-specific antibodies against specific adhesion proteins of the epidermis and dermal-epidermal junction. See Jordon R. E., et al., JAMA: 200, 751 (1967). Studies analyzing the role of T cells in the pathogenesis of bullous pemphigoid by analysis of PBL and skin blister T cells have found a predominance of CLA+ T cells expressing increased levels of Th2-cytokines like IL-4 and IL-13. See Teraki Y., et al., J Invest Dermatol: 117, 1097 (2001). In bullous pemphigoid patients following therapy with systemic corticosteroids, the frequency of CLA+, but not CLA−, interleukin-13-producing cells is significantly decreased. Decreases in CLA+ cells following corticosteroid treatment is associated with clinical improvement. See Teraki, ibid. Neutralization of IL-31 by an IL-31RA antagonist, e.g., antibody or fragment thereof or soluble receptor (IL-31RA and IL-31RA/OSMRbeta soluble receptors), may improve clinical outcome of bullous pemohigoid.

Alopecia Areata

Alopecia areata (AA) is regarded as a tissue-restricted autoimmune disease of hair follicles in which follicular activity is arrested because of the continued activity of lymphocytic infiltrates. AA results in patches of complete hair loss anywhere on the body, though actual loss of hair follicles does not occur, even in hairless lesions. Although clinical signs of inflammation are absent, skin biopsies from sites of active disease show perifollicular lymphocytic inflammation of primarily CD4+ cells, along with a CD8+ intrafollicular infiltrate. See Kalish R. S. & Gilhar A. J Investig Dermatol Symp Proc: 8, 164 (2003).

Studies have shown that scalp skin infiltrating CD4+ or CD8+ lymphocytes express CLA and, in peripheral blood of individuals with AA, the percent of CLA+ CD4+ or CD8+ lymphocytes is significantly higher than that of normal controls. Furthermore, patients with severe or progressive AA show a much higher CLA-positivity compared to patients recovering from the disease and a decrease in percent CLA+ cells parallels a good clinical course. See Yano S., et al., Acta Derm Venereol: 82, 82 (2002). These studies therefore suggest that CLA+ lymphocytes may play an important role in AA. Xenograft models have demonstrated that activated T cells are likely to play a role in the pathogenesis of AA. Lesional scalp from AA patients grafted onto nude mice regrows hair coincident with a loss of infiltrating lymphocytes from the graft and, transfer of activated lesional T cells to SCID mice can transfer hair loss to human scalp explants on SCID mice. See Kalish R. S. & Gilhar A. J Investig Dermatol Symp Proc: 8, 164 (2003).

A variety of immunomodulating therapies are part of the usual treatment for this disorder however none of these treatments have been consistent in their efficacy. See Tang L., et al., J Invest Dermatol: 120, 400 (2003); Tang L., et al., (2004); and Tang L., et al., J Am Acad Dermatol: 49, 1013 (2003). Neutralizing anti-IL-31RA antibody or fragment thereof or IL-31RA soluble receptor (IL-31RA and IL-31RA/OSMRbeta soluble receptors) may be effective to limit, reduce, inhibit, or prevent the effects of the development of AA.

Acne Vulgaris/Acne Rosacea

Acne vulgaris, a disorder of the pilosebaceous apparatus, is the most common skin problem of adolescence. Abnormalities in follicular keratinization are thought to produce the acne lesion. Acne rosacea is differentiated from acne vulagaris by the presence of red papules, pustules, cysts and extensive telangiectasias, but the absence of comedones (white heads). Increased sebum excretion from sebaceous glands is a major factor in the pathophysiology of acne vulgaris. Other sebaceous gland functions are also associated with the development of acne, including sebaceous proinflammatory lipids; different cytokines produced locally; periglandular peptides and neuropeptides, such as corticotrophin-releasing hormone, which is produced by sebocytes; and substance P, which is expressed in the nerve endings at the vicinity of healthy-looking glands of acne patients. See Zouboulis C. C. Clin Dermatol: 22, 360 (2004).

Although the pathophysiology of acne vulgaris and acne rosacea remains unknown, clinical observations and histopathologic studies suggest that inflammation of the pilosebaceous follicle may be central to the pathogenesis of rosacea and acne vulgarism Early studies on analysis of T cell subsets infiltrating rosacea legions indicated that the majority of T cells expressed CD4. See Rufli T. & Buchner S. A. Dermatologica: 169, 1 (1984).

CD4+ T cells produce IL-31 and IHC analysis of skin for IL-31 expression suggests that IL-31 is expressed in sebaceous and sweat glands. IL-31 stimulation of epidermal keratinocytes induces expression of chemokines which likely results in cellular infiltration suggesting that IL-31 may contribute to the pro-inflammatory response in skin. IL-31 may therefore contribute to the pathophysiology of acne rosacea and acne vulgaris. Accordingly, an IL-31RA antagonist, such as an anti-IL-31RA antibody or fragment thereof, or an IL-31RA soluble receptor (IL-31RA and IL-31RA/OSMRbeta soluble receptors) can be useful to treat, reduce the severity of, inhibit the progression of, ablate, and/or eliminate one or more symptoms associated with acne rosacea and acne vulgarism

Prurigo Nodularis

Prurigo nodularis is an eruption of lichenified or excoriated nodules caused by intractable pruritus that is difficult to treat. While chronic rubbing results in lichenification, and scratching in linear excoriations, individuals who pick and gouge at their itchy, irritated skin tend to produce markedly thickened papules known as prurigo nodules. Although prurigo nodularis is not specific to atopic dermatitis, many patients with these nodules also have an atopic reaction, which manifests as allergic rhinitis, asthma, or food allergy. T cells represent the majority of infiltrating cells in prurigo lesions and these lesions often represents the most pruritic skin lesion in atopy patients.

Topical treatment of prurigo nodularis with capsaicin, an anti-pruritic alkaloid that interferes with the perception of pruritis and pain by depletion of neuropeptides like substance P in small sensory cutaneous nerves, has proven to be an effective and safe regimen resulting in clearing of the skin lesions. See Stander S., et al., J Am Acad Dermatol: 44, 471 (2001). Studies of the itch response in NC/Nga mice using capsaicin treatment showed that the spontaneous development of dermatitis lesions was almost completely prevented. Furthermore, the elevation of serum IgE levels was significantly suppressed and infiltrating eosinophils and mast cell numbers in lesional skin of capsaicin treated mice were reduced. See Mihara K., et al., Br J Dermatol: 151, 335 (2004). The observations from this group suggest that scratching behaviour might contribute to the development of dermatitis by enhancing various immunological responses, therefore implying that prevention of the itch sensation and/or itch-associated scratching behaviour might be an effective treatment for AD. See Mihara K., et al., Br J Dermatol: 151, 335 (2004).

Chronic delivery of IL-31 induces pruritis and alopecia in mice followed by the development of skin lesions resembling dermatitis suggesting that IL-31 induces itching. See Dillon S. R., et al., Nat Immunol: 5, 752 (2004). The involvement of IL-31 was tested in induction of the itch response by two methods (i) capsaicin treatment of IL-31-treated mice and (ii) IL-31 treatment of Tac1 knockout mice, which have significantly reduced nociceptive pain responses because of lack of expression of neuropeptides in Example 5. In addition, whether neutralization of IL-31 in IL-31 treated mice could prevent pruritis and alopecia was tested in Example 5.

Skin-Tropic Viruses and Viral Associated Pruritis

Herpes Simplex Virus (HSV)-specific CD8+ T cells in the peripheral blood and HSV-specific CD8+ T cells recovered from herpes lesions express high levels of CLA where as non-skin-tropic herpes virus-specific CD8+ T cells lack CLA expression. See Koelle D. M., et al., J Clin Invest: 110, 537 (2002). HSV-2 reactive CD4+ T lymphocytes also express CLA, but at levels lower than those previously observed for CD8+ T lymphocytes. See Gonzalez J. C., et al., J Infect Dis: 191, 243 (2005). Pruritis has also been associated with herpes viral infections (See Hung K. Y., et al., Blood Purif: 16, 147 (1998), though other viral diseases, like HIV, have also been associated with pruritic skin lesions. Severe, intractable pruritus, often associated with erythematopapular skin lesions and hypereosinophilia, is a condition observed in some nonatopic, HIV-infected patients 36. See Singh F. & Rudikoff D, Am J Clin Dermatol; 4, 177 (2003); and Milazzo F., Piconi S., et al., Allergy: 54, 266 (1999).

The association of skin-tropic viruses with pruritis and CLA+ T cells suggests that IL-31 producing T cells may be involved in the pathophysiology of viral infections.

Inflammation is a protective response by an organism to fend off an invading agent. Inflammation is a cascading event that involves many cellular and humoral mediators. On one hand, suppression of inflammatory responses can leave a host immunocompromised; however, if left unchecked, inflammation can lead to serious complications including chronic inflammatory diseases (e.g., rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease and the like), septic shock and multiple organ failure. Importantly, these diverse disease states share common inflammatory mediators. The collective diseases that are characterized by inflammation have a large impact on human morbidity and mortality. Therefore it is clear that anti-inflammatory molecules, such as anti-IL-31RA antibodies and fragments thereof, and IL-31RA soluble receptors as described herein, could have crucial therapeutic potential for a vast number of human and animal diseases, from asthma and allergy to autoimmunity and septic shock. As such, use of anti-inflammatory anti-IL-31RA antibodies and fragments thereof, and IL-31RA soluble receptors as described herein can be used therapeutically as IL-31RA antagonists for treating, reducing the severity of, inhibiting the progression of, and ablating diseases such as arthritis, endotoxemia, inflammatory bowel disease, psoriasis, related disease and the like.

IL-31 has been shown to induce several chemokine and cytokine genes in normal human epidermal keratinocytes (NHEKs), including genes encoding GROα, (CXCL1), TARC (CCl17), MIP3β, (CCL19), MDC (CCL22), MIP-3 (CCL23), MIP-1β (CCL4), and I-309. See Dillon S. R., et al., Nat Immunol: 5, 752 (2004). TARC and MDC bind CCR4, a chemokine receptor associated with Th2-type T cells and predominantly expressed by CLA+ T cells in peripheral blood. Both chemokines have been implicated in the recruitment of T cells into the skin of AD patients suggesting that these chemokines contribute to the inflammatory process associated with the pathogenesis of AD. See Example 10 for a model to measure the reduction in TARC and MDC levels by administering an IL-31 antagonist.

Psoriasis is a chronic skin condition that affects more than seven million Americans. Psoriasis occurs when new skin cells grow abnormally, resulting in inflamed, swollen, and scaly patches of skin where the old skin has not shed quickly enough. Plaque psoriasis, the most common form, is characterized by inflamed patches of skin (“lesions”) topped with silvery white scales. Psoriasis may be limited to a few plaques or involve moderate to extensive areas of skin, appearing most commonly on the scalp, knees, elbows and trunk. Although it is highly visible, psoriasis is not a contagious disease. The pathogenesis of the diseases involves chronic inflammation of the affected tissues. Anti-IL-31RA antibodies and fragment thereof and soluble receptors (IL-31RA and IL-31RA/OSMRbeta soluble receptors) could serve as a valuable therapeutic to treat, inhibit the progression of, reduce the severity of, reduce inflammation and pathological effects in psoriasis, other inflammatory skin diseases, skin and mucosal allergies, and related diseases.

Psoriasis is a T-cell mediated inflammatory disorder of the skin that can cause considerable discomfort. It is a disease for which there is no cure and affects people of all ages. Psoriasis affects approximately two percent of the populations of European and North America. Although individuals with mild psoriasis can often control their disease with topical agents, more than one million patients worldwide require ultraviolet or systemic immunosuppressive therapy. Unfortunately, the inconvenience and risks of ultraviolet radiation and the toxicities of many therapies limit their long-term use. Moreover, patients usually have recurrence of psoriasis, and in some cases rebound, shortly after stopping immunosuppressive therapy.

The present invention provides a method for inhibiting activation or differentiation of monocytes/macrophages. Monocytes are incompletely differentiated cells that migrate to various tissues where they mature and become macrophages. Macrophages play a central role in the immune response by presenting antigen to lymphocytes and play a supportive role as accessory cells to lymphocytes by secreting numerous cytokines. Macrophages can internalize extracellular molecules and upon activation have an increased ability to kill intracellular microorganisms and tumor cells. Activated macrophages are also involved in stimulating acute or local inflammation.

The molecules of the present invention have particular use in the monocyte/macrophage arm of the immune system. Methods are known that can assess such activity. For example, interferon gamma (IFN-γ) is a potent activator of mononuclear phagocytes. For example, an increase in expression of IL-31RA upon activation of THP-1 cells (ATCC No. TIB-202) with interferon gamma could suggest that this receptor is involved in monocyte activation. Monocytes are incompletely differentiated cells that migrate to various tissues where they mature and become macrophages. Macrophages play a central role in the immune response by presenting antigen to lymphocytes and play a supportive role as accessory cells to lymphocytes by secreting numerous cytokines. Macrophages can internalize extracellular molecules and upon activation have an increased ability to kill intracellular microorganisms and tumor cells. Activated macrophages are also involved in stimulating acute or local inflammation. Moreover, monocyte-macrophage function has been shown to be abnormal in a variety of diseased states. For example see, Johnston, R B, New Eng. J. Med. 318:747-752, 1998.

One of skill in the art would recognize that agonists of IL-31RA receptor, such as agonist IL-31RA antibody, are useful. For example, depressed migration of monocytes has been reported in populations with a predisposition to infection, such as newborn infants, patients receiving corticosteroid or other immunosuppressive therapy, and patients with diabetes mellitus, burns, or AIDS. Agonists for IL-31RA, such as agonist IL-31RA antibody, could result in an increase in the ability of monocytes to migrate and possibly prevent infection in these populations. There is also a profound defect of phagocytic killing by mononuclear phagocytes from patients with chronic granulomatous disease. This results in the formation of subcutaneous abscesses, as well as abscesses in the liver, lungs, spleen, and lymph nodes. An agonist of IL-31RA receptor such as agonist IL-31RA antibody, could correct or improve this phagocytic defect. In addition, defective monocyte cytotoxicity has been reported in patients with cancer and Wiskott-Aldrich syndrome (eczema, thrombocytopenia, and recurrent infections). Activation of monocytes by agonists of IL-31RA receptor, such as agonist IL-31RA antibody, could aid in treatment of these conditions. The monocyte-macrophage system is prominently involved in several lipid-storage diseases (sphingolipidoses) such as Gaucher's disease. Resistance to infection can be impaired because of a defect in macrophage function, which could be treated by agonists to IL-31RA receptor such as agonist IL-31RA antibody.

Using methods known in the art, and disclosed herein, one of skill could readily assess the activity of IL-31RA agonists and antagonists in diseases that have a high correlation of CLA+ T cells. In addition, as IL-31 is expressed in a T-cell, macrophage and monocyte-specific manner, and these diseases involve abnormalities in monocytic cells, such as cell proliferation, function, localization, and activation, the polynucleotides, polypeptides, and antibodies of the present invention can be used to as diagnostics to detect such monocytic cell abnormalities, and indicate the presence of disease. Such methods involve taking a biological sample from a patient, such as blood, saliva, or biopsy, and comparing it to a normal control sample. Histological, cytological, flow cytometric, biochemical and other methods can be used to determine the relative levels or localization of IL-31, or cells expressing IL-31, i.e., monocytes, in the patient sample compared to the normal control. A change in the level (increase or decrease) of IL-31 expression, or a change in number or localization of monocytes (e.g., increase or infiltration of monocytic cells in tissues where they are not normally present) compared to a control would be indicative of disease. Such diagnostic methods can also include measuring TARC and MDC, for example. Such methods are well known in the art and disclosed herein.

IL-31RA antagonists, such as anti-IL-31RA antibodies, can be used to modulate the immune system by binding IL-31RA receptor, and thus, preventing the binding of IL-31 with endogenous IL-31 receptor. Alternatively, IL-31RA antagonists, such as soluble IL-31RA and IL-31RA/OSMRbeta receptors, can also be used to modulate the immune system by inhibiting the binding of IL-31 with the endogenous IL-31RA receptor. Accordingly, the present invention includes the use of IL-31RA antibodies and fragments thereof as well as IL-31RA soluble receptors (IL-31RAa dn IL-31RA/OSMRbeta) which can be administered to a subject which has excess IL-31. IL-31RA antagonists (e.g., anti-IL-31RA antibodies and fragments thereof and soluble IL-31RA and soluble IL-31RA/OSMRbeta receptors) can be also used to treat diseases that have a high correlation of CLA+ T cells. Suitable subjects include mammals, such as humans.

IL-31 has been shown to be expressed in activated mononuclear cells, and may be involved in regulating inflammation. As such, antibodies and soluble receptors of the present invention can be assayed and used for their ability to modify inflammation, or can be used as a marker for inflammation. Methods to determine proinflammatory and anti-inflammatory qualities of IL-31 are known in the art and discussed herein. Moreover, it may be involved in up-regulating the production of acute phase reactants, such as serum amyloid A (SAA), α1-antichymotrypsin, and haptoglobin, and that expression of IL-31RA receptor may be increased upon injection of lipopolysaccharide (LPS) in vivo that are involved in inflammatory response (Dumoutier, L. et al., Proc. Nat'l. Acad. Sci. 97:10144-10149, 2000). Production of acute phase proteins, such as SAA, is considered a short-term survival mechanism where inflammation is beneficial; however, maintenance of acute phase proteins for longer periods contributes to chronic inflammation and can be harmful to human health. For review, see Uhlar, C M and Whitehead, A S, Eur. J. Biochem. 265:501-523, 1999, and Baumann H. and Gauldie, J. Immunology Today 15:74-80, 1994. Moreover, the acute phase protein SAA is implicated in the pathogenesis of several chronic inflammatory diseases, is implicated in atherosclerosis and rheumatoid arthritis, and is the precursor to the amyloid A protein deposited in amyloidosis (Uhlar, C M and Whitehead, supra.). Thus, where a ligand such as IL-31 that acts as a pro-inflammatory molecule and induces production of SAA, antagonists would be useful in treating inflammatory disease and other diseases associated with acute phase response proteins induced by the ligand. Such antagonists are provided by the present invention. For example, a method of reducing inflammation comprises administering to a mammal with inflammation a therapeutically effective amount of a composition comprising anti-IL-31RA antibody (e.g., neutralizing antibody) or fragment thereof, or a soluble receptor (e.g., IL-31RA and IL-31RA/OSMRbeta soluble receptors) that is sufficient to reduce inflammation. Moreover, a method of suppressing an inflammatory response in a mammal with inflammation can comprise: (1) determining a level of serum amyloid A protein; (2) administering a composition comprising an anti-IL-31RA antibody as described herein or soluble receptor (IL-31RA and IL-31RA/OSMRbeta soluble receptors) in an acceptable pharmaceutical carrier; (3) determining a post administration level of serum amyloid A protein; (4) comparing the level of serum amyloid A protein in step (1) to the level of serum amyloid A protein in step (3), wherein a lack of increase or a decrease in serum amyloid A protein level is indicative of suppressing an inflammatory response.

Moreover, anti-IL-31RA antibodies and fragments thereof that block the binding and/or signaling of IL-31 to IL-31RA, and soluble IL-31RA receptors (IL-31RA and IL-31RA/OSMRbeta) that bind IL-31 and thus prevent the binding of IL-31 to cellular-based IL-31RA are useful to antagonize or block signaling of IL-31 and are thus useful in the treatment of, inhibit the progression of, reduce the severity of, reduce one or more symptoms associated with Contact dermatitis, Drug induced delayed type cutaneous allergic reactions, Toxic epidermal necrolysis, Cutaneous T cell Lymphoma, Bullous pemphigoid, Alopecia aereata, Vitiligo, Acne Rosacea, Prurigo nodularis, Scleroderma, and Herpes simplex virus.

Anti-IL-31RA antibodies, and soluble IL-31RA (IL-31RA and IL-31RA/OSMRbeta soluble receptors) comprising receptors are useful as antagonists of IL-31. Such antagonistic effects can be achieved by direct neutralization or binding of its natural ligand. In addition to antagonistic uses, the soluble receptors can bind IL-31 and act as carrier or carrier proteins, in order to transport IL-31 to different tissues, organs, and cells within the body. As such, the soluble receptors can be fused or coupled to molecules, polypeptides or chemical moieties that direct the soluble-receptor-Ligand complex to a specific site, such as a tissue, specific immune cell, monocytes, or tumor. For example, in acute infection or some cancers, benefit may result from induction of inflammation and local acute phase response proteins. Thus, the soluble receptors described herein or antibodies (and fragments thereof) of the present invention can be used to specifically direct the action of a pro-inflammatory IL-31 ligand. See, Cosman, D. Cytokine 5: 95-106, 1993; and Fernandez-Botran, R. Exp. Opin. Invest. Drugs 9:497-513, 2000.

IL-31 may also be used within diagnostic systems for the detection of circulating levels of ligand, and in the detection of acute phase inflammatory response. Within a related embodiment, antibodies or other agents that specifically bind to IL-31, e.g., soluble IL-31RA and soluble IL-31RA/OSMRbeta, can be used to detect circulating IL-31 polypeptides. Elevated or depressed levels of ligand or receptor polypeptides may be indicative of pathological conditions, including inflammation or cancer. Moreover, detection of acute phase proteins or molecules such as IL-31 can be indicative of a chronic inflammatory condition in certain disease states (e.g., rheumatoid arthritis). Detection of such conditions serves to aid in disease diagnosis as well as help a physician in choosing proper therapy.

Generally, the dosage of administered IL-31RA antibody or fragment thereof or soluble IL-31RA receptor or soluble IL-31RA/OSMRbeta receptor will vary depending upon such factors as the patient's age, weight, height, sex, general medical condition and previous medical history. Typically, it is desirable to provide the recipient with a dosage of IL-31RA antibody or fragment thereof or soluble IL-31RA receptor or soluble IL-31RA/OSMRbeta receptor which is in the range of from about 1 pg/kg to 10 mg/kg (amount of agent/body weight of patient), although a lower or higher dosage also may be administered as circumstances dictate. One skilled in the art can readily determine such dosages, and adjustments thereto, using methods known in the art.

Administration of IL-31RA antibody or fragment thereof or soluble IL-31RA receptor or soluble IL-31RA/OSMRbeta receptor to a subject can be topical, intradermal, inhalant, intravenous, intraarterial, intraperitoneal, intramuscular, subcutaneous, intrapleural, intrathecal, by perfusion through a regional catheter, or by direct intralesional injection. When administering therapeutic proteins by injection, the administration may be by continuous infusion or by single or multiple boluses.

Additional routes of administration include oral, mucosal-membrane, pulmonary, and transcutaneous. Oral delivery is suitable for polyester microspheres, zein microspheres, proteinoid microspheres, polycyanoacrylate microspheres, and lipid-based systems (see, for example, DiBase and Morrel, “Oral Delivery of Microencapsulated Proteins,” in Protein Delivery: Physical Systems, Sanders and Hendren (eds.), pages 255-288 (Plenum Press 1997)). The feasibility of an intranasal delivery is exemplified by such a mode of insulin administration (see, for example, Hinchcliffe and Illum, Adv. Drug Deliv. Rev. 35:199 (1999)). Dry or liquid particles comprising IL-31RA antibody or fragment thereof or soluble IL-31RA receptor or soluble IL-31RA/OSMRbeta receptor can be prepared and inhaled with the aid of dry-powder dispersers, liquid aerosol generators, or nebulizers (e.g., Pettit and Gombotz, TIBTECH 16:343 (1998); Patton et al., Adv. Drug Deliv. Rev. 35:235 (1999)). This approach is illustrated by the AERX diabetes management system, which is a hand-held electronic inhaler that delivers aerosolized insulin into the lungs. Studies have shown that proteins as large as 48,000 kDa have been delivered across skin at therapeutic concentrations with the aid of low-frequency ultrasound, which illustrates the feasibility of trascutaneous administration (Mitragotri et al., Science 269:850 (1995)). Transdermal delivery using electroporation provides another means to administer IL-31RA antibody or fragment thereof or soluble IL-31RA receptor or soluble IL-31RA/OSMRbeta receptor (Potts et al., Pharm. Biotechnol. 10:213 (1997)).

A pharmaceutical composition comprising a IL-31RA antibody or fragment thereof (antagonist and agonist) or a soluble IL-31RA receptor or a soluble IL-31RA/OSMRbeta receptor can be formulated according to known methods to prepare pharmaceutically useful compositions, whereby the therapeutic proteins are combined in a mixture with a pharmaceutically acceptable carrier. A composition is said to be a “pharmaceutically acceptable carrier” if its administration can be tolerated by a recipient patient. Sterile phosphate-buffered saline is one example of a pharmaceutically acceptable carrier. Other suitable carriers are well-known to those in the art. See, for example, Gennaro (ed.), Remington's Pharmaceutical Sciences, 19th Edition (Mack Publishing Company 1995).

For purposes of therapy, an IL-31RA antibody or fragment thereof (antagonist and agonist) or a soluble IL-31RA receptor or a soluble IL-31RA/OSMRbeta receptor and a pharmaceutically acceptable carrier are administered to a patient in a therapeutically effective amount. A combination of an IL-31RA antibody (antagonist and agonist) or a soluble IL-31RA receptor (e.g., IL-31RA homodimer and a zcytor17/OSMRbeta heterodimer) and a pharmaceutically acceptable carrier is said to be administered in a “therapeutically effective amount” if the amount administered is physiologically significant. An agent is physiologically significant if its presence results in a detectable change in the physiology of a recipient patient. For example, an agent used to treat inflammation is physiologically significant if its presence alleviates at least a portion of the inflammatory response.

A pharmaceutical composition comprising an IL-31RA antibody or fragment thereof (antagonist and agonist) or a soluble IL-31RA receptor or a soluble IL-31RA/OSMRbeta receptor can be furnished in liquid form, in an aerosol, or in solid form. Liquid forms, are illustrated by injectable solutions, aerosols, droplets, topological solutions and oral suspensions. Exemplary solid forms include capsules, tablets, and controlled-release forms. The latter form is illustrated by miniosmotic pumps and implants (Bremer et al., Pharm. Biotechnol. 10:239 (1997); Ranade, “Implants in Drug Delivery,” in Drug Delivery Systems, Ranade and Hollinger (eds.), pages 95-123 (CRC Press 1995); Bremer et al., “Protein Delivery with Infusion Pumps,” in Protein Delivery: Physical Systems, Sanders and Hendren (eds.), pages 239-254 (Plenum Press 1997); Yewey et al., “Delivery of Proteins from a Controlled Release Injectable Implant,” in Protein Delivery: Physical Systems, Sanders and Hendren (eds.), pages 93-117 (Plenum Press 1997)). Other solid forms include creams, pastes, other topological applications, and the like.

An IL-31RA antibody or fragment thereof (antagonist and agonist) or a soluble IL-31RA receptor or a soluble IL-31RA/OSMRbeta receptor can be encapsulated within liposomes using standard techniques of protein microencapsulation (see, for example, Anderson et al., Infect. Immun. 31:1099 (1981), Anderson et al., Cancer Res. 50:1853 (1990), and Cohen et al., Biochim. Biophys. Acta 1063:95 (1991), Alving et al. “Preparation and Use of Liposomes in Immunological Studies,” in Liposome Technology, 2nd Edition, Vol. III, Gregoriadis (ed.), page 317 (CRC Press 1993), Wassef et al., Meth. Enzymol. 149:124 (1987)). As noted above, therapeutically useful liposomes may contain a variety of components. For example, liposomes may comprise lipid derivatives of poly(ethylene glycol) (Allen et al., Biochim. Biophys. Acta 1150:9 (1993)).

Other dosage forms can be devised by those skilled in the art, as shown, for example, by Ansel and Popovich, Pharmaceutical Dosage Forms and Drug Delivery Systems, 5^(th) Edition (Lea & Febiger 1990), Gennaro (ed.), Remington's Pharmaceutical Sciences, 19^(th) Edition (Mack Publishing Company 1995), and by Ranade and Hollinger, Drug Delivery Systems (CRC Press 1996).

The complete disclosure of all patents, patent applications, and publications, and electronically available material (e.g., GenBank amino acid and nucleotide sequence submissions) cited herein are incorporated by reference. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described, for variations obvious to one skilled in the art will be included within the invention defined by the claims.

EXAMPLES Example 1 Determination of Human Primary T Cell Types that Express IL-31 Upon Stimulation

Selection of Study Subjects and Biopsies

Twelve patients with AD (moderate to severe disease; median age was 32 years old with skin involvement of 5-45%), 6 patients with psoriasis (median age was 56 years old with skin involvement of 10-65%) and 12 healthy individuals (median age 34 years) were included in A study after informed consent. None of the patients had received any systemic corticosteroids previously. All patients were off topical corticosteroids for one week before their skin biopsy or blood drawing. Two mm punch biopsies were taken from 1) acute erythematous AD lesions of less than three days' onset, 2) chronic, lichenified AD lesions of greater than two weeks' duration, 3) chronic psoriasis lesions, and 4) normal skin. The skin samples were immediately frozen at −70° C. for immunohistochemistry or Western and immuno-dot blotting.

Isolation and Activation of Primary Human T Cell Subsets:

To isolate various T cell subsets, human PBMCs from the donors were isolated using standard Ficoll gradient centrifugation. Total T cells were then isolated using the T Cell Isolation Kit II (Miltenyi Biotec) according to the manufacturer's instructions. Separation efficiency was assessed using standard flow cytometry and determined to be >95% T cells. To separate CD45RA+ “naïve” T cells from the CD45RO+ “memory” T cells, the total T cell population was incubated with anti-CD45RO microbeads (Miltenyi Biotec) for 15 minutes at +4° C. and magnetically separated according to the manufacturers instructions. The naïve and memory T cell populations were determined to be >90% pure by flow cytometry.

CD45RO+ memory T cells are often tissue specific and cutaneous lymphocyte antigen (CLA) is used to differentiate skin-homing T cells from gut-homing T cells expressing α4/β7 on their surface. To determine which of these cell types produce IL-31, CLA+ T cells were isolated from total T cells, activated and conditioned media was collected for the IL-31 bioassay. To do this, total T cells were isolated and then incubated on ice for 20 minutes in 1 mL of a 1:50 dilution of anti-CLA-FITC antibody (PharMingen). Cells were then washed, resuspended in MACS buffer and incubated with anti-FITC microbeads (Miltenyi Biotec) for 15 minutes at +4° C. The cells were then washed, resuspended and magnetically separated over an LS column according to the manufacturer's instructions. The labeled T cells were later determined to be >80% pure while the CLA-depleted T cells were >98% CLA−. Both CLA+ and CLA− T cells were collected and cultured concurrently.

To activate the CD45RA+ and CD45RO+ T cell subsets, cells were cultured overnight in 24-well tissue culture plates pretreated with 2.0 μg/mL anti-CD3 antibody (Southern Biotechnology). The cells were plated at a concentration of 2.5×10⁶ cells/mL in tissue culture media (RPMI, 5% fetal bovine serum, L-Glutamine and Sodium Pyruvate (all Gibco)) supplemented with 2.0 μg/mL anti-CD28 (Southern Biotechnology) and placed in a +37° C. incubator. After four hours, half of the wells were harvested, cells pelleted and conditioned media frozen at −20° C. until time of IL-31 bioassay.

The CLA+ and CLA− T cell subsets were activated similarly in 48-well tissue culture plates that were pretreated with 2.0 μg/mL anti-CD3 antibody (Southern Biotechnology). The cells were activated for 16 hours or 24 hours in a +37° C. incubator at a concentration of 6.25×10⁵ cells/mL. Samples were harvested, cells pelleted and conditioned media frozen at −20° C. until time of IL-31 bioassay. For suboptimal activation, CLA+ T cells were cultured in plates pre-treated with 0.5 ug/ml of anti-CD3 antibody.

Human IL-31 Bioassay Protocol:

BAF3 cells transfected with hIL-31RA, hOSMRbeta, and KZ134 were grown to 5×10⁵ and 1×10⁶ cells/mL. Cells were washed with assay media (RPMI 1640, 10% FBS, L-Glutamine, Sodium Pyruvate, and Pen/Strep (all Gibco)) and resuspended at 3×10⁵ cell/mL in assay medium. In a 96-well opaque plate, hIL-31 standards were titered in duplicate from 600 pg/mL to 9.38 pg/mL in assay medium via a 100 μL/well, 1:2 serial dilution. Quality control standards were added in duplicate to the plate at 350 pg/mL and 35 pg/mL in 100 μL. Test samples were often diluted 1:2 or 1:4 and added in duplicate to the sample wells. 100 μL of the washed BAF3 cells were then added to each well for a final concentration of 3×10⁴ cells/well. The plate was then incubated for 16-24 hours at +37° C. in a 5% CO₂ incubator. The plate was then centrifuged at 1200 RPM for 5 minutes, media flicked off and 25 μL/well of lysis buffer (Promega) added to each well. After 10 minutes the plate was read on a luminometer (Berthold). The luminometer added 40 μL/well of luciferase substrate mix (Promega) and integrated the luminescence for a period of 4 seconds. Luminescence values were exported to a spreadsheet where they were analyzed and converted into picograms of IL-31 per 10⁶ cells per mL of volume. The data is summarized in Table 1.

Results of IL-31 Bioassay:

The results from the CD45RA+ and the CD45RO+ T cell samples revealed that IL-31 was primarily produced by activated CD45RO+ memory T cells. The CD45RA+ and CD45RO+ T cells from both donors produced no detectable IL-31 when unstimulated. However, the CD45RO+ samples from both donors #3 and #4 generated significant levels of IL-31 following a 24 hour activation with plate-bound anti-CD3 and soluble anti-CD28 (110.4 pg/10⁶ cells/mL and 145.6 pg/10⁶ cells/mL respectively). Conversely, when the CD45RA+ T cells from donors #3 and #4 were activated with anti-CD3 and anti-CD28, they produced very low amounts of IL-31 (13.1 pg/10⁶ cells/mL and 12.7 pg/10⁶ cells/mL respectively).

The CLA+ and CLA− T cell samples revealed that IL-31 seems to be made almost entirely by activated CLA+ T cells. The CLA− population of T cells (which includes naïve T cells, α4/β7 gut-homing memory T cells, and tissue uncommitted T cells) from both donors generated no detectable levels of IL-31 regardless of time point or activation condition. The CLA+ T cells on the other hand, generated very high levels of IL-31 when stimulated with 2.0 μg/mL plate-bound anti-CD3 antibody. Donor #5 generated 1385.7 pg/10⁶ cells/mL IL-31 by 16 hours and >1920 pg/10⁶ cells/mL by 24 hours. Donor #6 generated 121.3 pg/10⁶ cells/mL IL-31 at 16 hours and 328.9 pg/10⁶ cells/mL IL-31 at 24 hours. These results clearly demonstrate that of the T cell subsets, IL-31 seems to be made specifically by cutaneous (CLA+) T cells under standard activation conditions.

TABLE 1 IL-31 IL-31 (pg/10⁶ (pg/10⁶ Donor# Cell Type Activation cells/mL) cells/mL) 6 hr 24 hr 3 CD45RA+ αCD3 + αCD28 Below 13.1 Detection 3 CD45RO+ αCD3 + αCD28 8.6 110.4 4 CD45RA+ αCD3 + αCD28 6.7 12.7 4 CD45RO+ αCD3 + αCD28 11.9 145.6 16 hr 24 hr 5 CLA+ T Cells Unstimulated Below Below Detection Detection 5 CLA+ T Cells αCD3 1385.7 >1920 5 CLA− T Cells Unstimulated Below Below Detection Detection 5 CLA− T Cells αCD3 Below Below Detection Detection 6 CLA+ T Cells Unstimulated Below Below Detection Detection 6 CLA+ T Cells αCD3 121.3 328.9 6 CLA− T Cells Unstimulated Below Below Detection Detection 6 CLA− T Cells αCD3 Below Below Detection Detection

Example 2 Involvement in Initiation and Perpetuation of Contact Hyper-Sensitivity

Method I

BALB/c mice are painted on shaved mid-back with 25 μl of 0.5% DNFB dissolved (2,4, dinitro-fluoro-benzene, Sigma, St. Louis Mo.) in acetone:olive oil (4:1) solution using a pipettor. A vehicle control group receives 25 μl of acetone:olive oil only. After 5 days, mice are anaesthetized with isofluorane in an inhalation chamber and both ear pinnae of experimental and control animals are measured with an engineer's micrometer (Mitutoyo) to obtain a baseline measurement. Mice are then challenged by applying 10 μl of 0.25% DNFB in acetone:olive oil (4:1) to both sides of each ear of all mice. Contact hyper-sensitivity is measured at 24 h and 48 h later as the difference between the right ear (challenged) and the left ear (unchallenged). All measurements are done with an engineer's micrometer. Background values are determined by the difference in ear swelling between the challenged and unchallenged ears of naive mice.

Whole blood and serum for FACS and/or ELISA analysis are collected prior to sacrifice and ears are collected for histology.

Method II (Induces Th2 Responses)

BALB/c mice are painted on shaved mid-back with 100 ul of 0.5% FITC (fluorescein isothiocyanate) in a 1:1 solution of acetone/dibutyl phthalate (MSDS available using pipettor on days 1, 2 and 8. On day 13, mice are anaesthetized with isofluorane in an inhalation chamber and both ear pinnae of experimental and control animals are measured with an engineer's micrometer (Mitutoyo) to obtain a baseline measurement. Mice are challenged by applying 25 ul of 0.5% FITC (in 1:1 acetone/dibutyl phthalate) to the dorsal surface of each ear. Contact hyper-sensitivity is measured at 24 h and 48 h later as the difference between the right ear (challenged) and the left ear (unchallenged). All measurements are done with an engineer's micrometer. Background values are determined by the difference in ear swelling between the challenged and unchallenged ears of naive mice. Whole blood and serum for FACS and/or ELISA analysis are collected prior to sacrifice and ears are collected for histology.

Method III (Induces Th1 Responses)

BALB/c mice are painted on shaved mid-back with 25 ul of 2% oxazalone (in 4:1 acetone/olive oil) using pipettor. On day 7, mice are anaesthetized with isofluorane in an inhalation chamber and both ear pinnae of experimental and control animals are measured with an engineer's micrometer (Mitutoyo) to obtain a baseline measurement. Mice are challenged by applying 8 ul of oxazalone to the dorsal surface of each ear. Contact hyper-sensitivity is measured at 24 h and 48 h later as the difference between the right ear (challenged) and the left ear (unchallenged). All measurements are done with an engineer's micrometer. Background values are determined by the difference in ear swelling between the challenged and unchallenged ears of naive mice. Whole blood and serum for FACS and/or ELISA analysis are collected prior to sacrifice and ears are collected for histology.

Involvement of IL-31 in the initiation and perpetuation of contact hyper-sensitivity is tested using a neutralizing antibody against IL-31 both at the sensitization and challenge phases of the experiment.

Example 3 IL-31 Involvement in Atopic Dermatitis

Methods I (Sensitization of NC/Nga Mice)

Male NC/Nga mice were purchased from Charles River Laboratories, Japan. The mice were 4 weeks old on arrival and housed in SPF quarantine conditions for 4 weeks to acclimate. The mice were approximately 10-11 weeks old at the start of the antigen sensitization. Mice were anaesthetized with isofluorane and backs were shaved with electric clippers. Approximately 10 ug of Dermatophagoides pteronyssinus (Dp) (Indoor Biotechnologies, Charlottesville, Va., special order) extract was injected intradermally at the nape of the neck 3 times per week for 5 to 6 weeks until mice developed skin lesions. Control animals received 10 ul PBS intradermal injections 3 times per week. The Dp extract was prepared according to method by Matsuoka and colleagues. Matsuoka H., et al., Allergy: 58, 139 (2003). Briefly, 595 mg Dp lyophilized spent culture extract was dissolved in 12 mL sterile PBS (Gibco). Dp was mixed in a 50 mL Falcon tube on a shaking rocker for 30 minutes. The extract was spun for 10 minutes at 2000 rpm and the supernatant was collected and aliquoted into 1 mL cryovial tubes and stored at −20° C.

Method II (Sensitization of DO11.10 Mice)

DO11.10 transgenic mice were bred from an in-house colony and were between 9.5 and 14 weeks old at start of antigen sensitization. Twenty-four hours prior to epicutaneous sensitization mice were anaesthetized with isofluorane and the entire trunk (back and abdomen) of mice were shaved with electric clippers. The mice were then tape stripped with Elastin surgical tape (Johnson and Johnson) on the back. One cm² sterile gauze patches were wetted with either 500 ug ovalbumin (Calbiochem 32467) or sterile PBS (Gibco) and adhered to left backside of mice with DuoDerm Extra Thin Dressing (ConvaTec 187932). The patch and dressing were then covered in a body wrap of the Elastin surgical tape so mice could not remove or destroy the patches. Patches were worn for 7 days and removed. The mice were rested for two weeks before having another round of epicutaneous sensitization. Mice received a total of three one-week sensitizations.

Results

Immunohistochemical analysis of IL-31RA expression in lesional and non-lesional skin from dust mite sensitized NC/Nga and OVA sensitized DO11.10 animals showed that IL-31RA is expressed by epidermal keratinocytes in mice, however no significant difference in levels of expression can be found between antigen sensitized versus PBS sensitized animals.

Example 4 IL-31 Involvement Delayed Type Hypersensitivity

Methods

To generate a DTH response, mice were sensitized to antigen on day 0 by subcutaneous immunization at the base of the tail with 100 ug ovalbumin (OVA) in complete Freund's adjuvant (CFA, 50-100 μl total volume). One week later mice were anesthetized with isofluorane in an inhalation chamber and both ear pinnae of experimental and control animals were measured with an engineer's micrometer (Mitutoyo) to obtain a baseline measurement. Mice were challenged intradermally with 10 ug OVA in PBS in a total volume of 10 μl into the left ear pinnae, just below the skin without hitting any veins. As a control, mice also received an injection of 10 μl PBS in the right ear pinnae. In some cases, a separate control group given an i.d. injection of OVA in the ear may also be treated with topical corticosteroids as a positive control to inhibit the reaction. At 24 and 48 hr after challenge, mice were anesthetized and ear thickness was measured. Results were expressed as: Specific ear swelling=(24 hr measurement−0 hr measurement) for experimental ear−(24 hr measurement−0 hr measurement) for negative control ear. Induration, the hallmark of DTH, is detectable by 18 hours after injection of sensitized antigen and is maximal by 24-48 hours. The lag in the onset of palpable induration is the reason for naming the response “delayed type.”

Results

IL-31 transgenic mice were tested for DTH, however, due to an increase in ear thickness in un-challenged IL-31 transgenic animals, no statistically significant difference in DTH could be determined between IL-31 Tg animals compared to wildtype controls. IL-31RA knockout animals were also tested in a DTH response and no significant difference in the DTH response could be observed between receptor knockout and wildtype animals.

Example 5 IL-31 Involvement in Induction of the Itch Response

Methods I (IL-31 Treatment of Capsaicin Pre-Treated Mice)

Ten week old BALB/c animals (CRL) were anaesthetized and injected with a long-lasting analgesic agent, bupranorphine hydrochloride, subcutaneously at 0.1 mg/kg before injection of 0.25 ml of 4 mg/ml solution of capsaicin in 10% ethanol+10% Tween-80 in saline subcutaneously into scruff of neck. Animals were kept anaesthetized for at least 30 min following neurotoxin treatment. Forty-eight hours later, 14-day osmotic pumps were implanted subcutaneously for continuous delivery of 20 ug/day of IL-31 for 14 days. Mice were monitored daily for 6 days for alopecia and pruritis using the following criteria: 0=no scratching, animal appears normal, 1=thinning of coat in small areas, scratching noted, 2=minor hair loss (small patches), scratching, 3=moderate hair loss, scratching, and 4=severe hair loss, excessive scratching.

Results demonstrated that while non-capsaicin-treated mice showed a mean scratch/hairloss score of 2.625 following three days of IL-31 delivery, capsaicin-treated mice showed a significantly lower score of 1. Thus mice treated with capsaicin prior to IL-31 delivery showed both a delay in incidence of scratching and hairloss and a lower score in the intensity of scratching and hairloss over the six days of the experiment. These data suggest that IL-31 does induce some neuronal component that contributes to the alopecia and pruritis induced by IL-31. Therefore, neutralization of IL-31 may decrease the incidence and intensity of itch, and therefore dermatitis, in patients suffering from skin disorders that involve itch.

Method II (IL-31 Treatment of Tac1 Gene Deficient Mice)

Mice that are homozygous null for the Tac1 gene express no detectible substance P or neurokinin A. These mice have significantly reduced nociceptive pain responses to moderate to intense stimuli and are therefore a useful tool for studying the contribution of tachykinin peptides to pain/itch processing and inflammatory disease states. Twelve week old, Tac1 knockout mice were implanted with 14-day osmotic pumps delivering 1 ug/day of IL-31 protein and observed daily for alopecia and pruritis using the following criteria: 0=no scratching, animal appears normal, 1=thinning of coat in small areas, scratching noted, 2=minor hair loss (small patches), scratching, 3=moderate hair loss, scratching, and 4=severe hair loss, excessive scratching.

Results of this study show that Tac1 deficient mice were less susceptible to IL-31 induced scratching/hairloss compared to wildtype control mice. While 100% (10/10) of wildtype mice had developed evidence of scratching and hairloss by day 6 of IL-31 treatment, only 33.3% (2/6) Tac1 deficient mice were showing signs of scratching and hairloss at the same time-point. These data show that IL-31 induces a neuronal component that contributes to the scratch/hairloss phenotype in IL-31-treated mice and neutralization of IL-31 may decrease the incidence and intensity of scratching in the context of dermatitis.

Method III (Effect of Administration of IL-31 Neutralizing Antibody on IL-31 Treated Mice)

Normal female BALB/c mice (CRL) approximately 8 to 12 weeks old were implanted subcutaneously with 14-day osmotic pumps (Alzet, #2002) delivering 1 ug/day mIL-31. Groups of mice received intraperitoneal (i.p.) injections of rat anti-mouse IL-31 monoclonal antibody 10 mg/kg (200 ug/mouse) twice weekly starting 1 week prior to IL-31 delivery. Control groups of mice received i.p. injections of vehicle (PBS/0.1% BSA) with the identical dosing schedules. Mice were scored daily for alopecia and pruritis using the following criteria: 0=no scratching, animal appears normal, 1=thinning of coat in small areas, scratching noted, 2=minor hair loss (small patches), scratching, 3=moderate hair loss, scratching, and 4=severe hair loss, excessive scratching.

In all experiments, mice treated with rat anti-mIL-31 mAb had a delay in onset of symptoms of approximately 5 to 7 days and a lower overall score for alopecia and pruritis. All groups of mAb treated mice (regardless of dose frequency or concentration) developed alopecia and pruritis similar to control mice by 13 day of the study. These data suggest that neutralization of IL-31 can delay the onset of the scratch/hairloss response induced by IL-31.

Example 6 Immunohistochemical (IHC) Staining of IL-31 in Skin Lesions from Uninvolved Psoriatic, and Atopic Dermatitis

Uninvolved psoriatic, atopic dermatitis and normal skin were tested for the IL-31 ligand by IHC. Positive control cells consisted of BHK cells transfected with IL-31. Negative controls performed included: (1) un-transfected BHK cells, (2) staining representative tissues and cells with protein A purified Normal Rabbit serum and detecting antibody binding as usual. Antibody reagent was E5758 (Rabbit anti-huIL-31 CEE, Aff. Purified at 1.0 mg/ml). Control cells included C02-6020: BHK cells expressing zcytor17 Lig hu-CEE/21, and a BHK wild type. Tissues tested included acute atopic dermatitis skin samples, chronic atopic dermatitis skin samples, unaffected area skin samples, and normal control skin samples and other in-house control samples.

The cells and tissues described above were fixed overnight in 10% NBF and embedded in paraffin using standard techniques.

Five μM sections were baked at 61° C. for 30 min for tissue adhesion. Slides were subsequently dewaxed in 3×5′ in xylene and rehydrated through graded alcohols as follows: 2×2′ in 100% EtOH, 2×2′ in ×95% EtOH, 1×2′ in 70% EtOH. Slides were rinsed in dH20, and then heat induced epitope retrieval (HIER) was performed for 20 minutes under steam followed by 20 minutes cooling to RT in 10 mM Tris, 1 mM EDTA, pH 9.0

Slides were loaded onto a DakoCytomation Autostainer. Slides were rinsed with TBS/Tween buffer (TBST), prepared as recommend by manufacturer. Endogenous biotin was blocked with a 10 minute incubation in avidin solution, washed in TBST followed by a 10 minute incubation in biotin solution. Slides were washed in TBST. A protein block (PBSB) (0.5% Blocking Powder in PBS, Perkin Elmer NEL700001KT.) was applied for 30 minutes and rinsed off slides. The primary antibody was diluted to 500 ng/ml and was applied for 60 minutes in ChemMate Antibody Dilution Buffer (part # ADB250, Ventana Medical systems).

Tissues washed twice in TBST, and then incubated 45 minutes in biotinylated Goat anti-Rabbit Ab, 750 ng/ml in PBSB (catalog #BA-1000, Vector Labs). Slides washed twice in TBST. Vectastain Elite ABC Reagent (catalog # PK-7100, Vector Labs) was incubated for 45 minutes. Slides washed twice in TBST. Signals were developed with DAB+ (catalog # K-3468, DakoCytomation) for 10 minutes at room temperature. Tissue slides were then counterstained in hematoxylin (catalog # H-3401 Vector Labs), dehydrated and coverslipped in VectorMount (catalog # H-5000, Vector Labs).

Results

Cell Controls:

BHK cells transfected with IL-31 was positively stained with IL-31 antibody E5758 while un-transfected cells was negative for this antibody. The same transfected and un-transfected cells were negative with anti-rabbit sera.

2) Atopic Dermatitis Skin Analysis:

The staining pattern for IL31 in the AD skin samples is identical to that of psoriasis skins reported previously: keratinocyte and CD3 positive T-cells stained negative for IL31. A weak but rather uniform staining of the epithelial cells in the secretory portion of the sweat glands was present, but a strong signal was observed in the inner layer of epithelium in the duct portion. Sebaceous gland was positive for IL31. There was no difference in the IL31 staining between AD and normal skin.

Immunohistochemical (IHC) staining of uninvolved psoriatic, atopic dermatitis and normal skin showed strong staining of IL-31 in the holocrine secretion of the sebaceous glands. Considering the phenotype of IL 31 transgenic mice, it is interesting to note that the sebaceous glands originate as an epithelial bud from the outer root sheath of hair follicles. In addition to sebaceous glands weak but rather uniform staining of IL-31 was observed in the epithelial cells in the secretory portion of the sweat glands and a strong signal in the inner layer of epithelium was observed in the duct portion of sweat glands.

Example 7 Immunohistochemical (IHC) Staining of IL-31RA in Uninvolved Psoriatic, and Atopic Dermatitis

Uninvolved psoriatic, atopic dermatitis and normal skin were tested for the IL-31RA by IHC. Positive control cells consisted of BHK cells dual transfected with IL-31RA and OSMR. Negative controls performed included: (1) un-transfected BHK cells, (2) staining representative tissues and cells with protein A purified Normal Rabbit serum and detecting antibody binding as usual. Antibody reagent was E6292 (Rabbit anti-huIL-31RAs-CEE v. 4 at 1.33 mg/ml). Control cells included C02-5117 BHK cells expressing human IL-31RA and human OSMR (Total cells in the pellet: 3.9×10⁶, vitality was >90%) and C04-1587: BHK wild type (Total cells in the pellet: 5×10⁶). Other tissues examined included: 5 Acute atopic dermatitis skin samples, 10 Chronic atopic dermatitis skin samples, 10 Unaffected area skin samples, Normal control skin samples, and other in-house skin samples.

The cells and tissues described above were fixed overnight in 10% NBF and embedded in paraffin using standard techniques.

Five μM sections were baked at 61° C. for 30 min for tissue adhesion. Slides were subsequently dewaxed in 3×5′ in xylene and rehydrated through graded alcohols as follows: 2×2′ in 100% EtOH, 2×2′ in ×95% EtOH, 1×2′ in 70% EtOH. Slides were rinsed in dH20, and then heat induced epitope retrieval (HIER) was performed for 20 minutes under steam followed by 20 minutes cooling to RT in 10 mM Tris, 1 mM EDTA, pH 9.0

Slides were loaded onto a DakoCytomation Autostainer. Slides were rinsed with TBS/Tween buffer (TBST), prepared as recommend by manufacturer. Endogenous biotin was blocked with a 10-minute incubation in avidin solution, washed in TBST followed by a 10-minute incubation in biotin solution. Slides were washed in TBST. A protein block (PBSB) (0.5% Blocking Powder in PBS, Perkin Elmer NEL700001KT.) was applied for 30 minutes and rinsed off slides. Primary antibodies diluted from 665 ng/ml to 1330 ng/ml for IL31RA were applied for 60 minutes in ChemMate Antibody Dilution Buffer (part # ADB250, Ventana Medical systems).

Tissues were washed twice in TBST, and then incubated 45 minutes in biotinylated Goat anti-Rabbit Ab, 750 ng/ml in PBSB (catalog #BA-1000, Vector Labs). Slides were washed twice in TBST. Vectastain Elite ABC Reagent (catalog # PK-7100, Vector Labs) was incubated for 45 minutes. Slides were washed twice in TBST. Signals were developed with DAB+ (catalog # K-3468, DakoCytomation) for 10 minutes at room temperature. Tissue slides were then counterstained in hematoxylin (catalog # H-3401 Vector Labs), dehydrated and coverslipped in VectorMount (catalog # H-5000, Vector Labs).

Results are shown in Table 2.

TABLE 2 Results of IHC for IL-31RA in Skin Biopsies from Acute and Uninvolved AD Compared to Normal Volunteers IL-31RA IHC CASE ID SCORE* CD3 IHC SCORE* AD-1 2-3 0-1 AD-2 2-3 2 AD-3 2-3 1-2 AD-4 3 1 AD-5 2 2 UAD-1 1-2 1 UAD-2 1 0-1 UAD-3 ND ND UAD-4 ND ND UAD-5 1-2 0-1 UAD-6 2-3 ND UAD-7 2 1 UAD-8 1 1 UAD-9 1-2 1 UAD-10 2 ND Normal-1 1 0-1 Normal-2 0-1 0-1 Normal-3 1 0-1 Abbreviations: AD: atopic dermatitis; UAD: uninvolved AD; ND: Not Done *IHC signal was scored from 0 (no signal) to 4 (intense signal)

There was a slight up regulation of IL31RA in the epidermis of AD skin samples. Possibly a small percentage of CD3 positive T-cells were positive for IL31RA in the AD skins. There were CLA positive cells in all skin samples tested. AD skins may have more CLA positive cells than that of the normal or UAD samples.

IL-31RA was also expressed in the epithelial cells of eccrine sweat glands with the cuboidal epithelial cells in the secretory portion of the eccrine glands demonstrating slightly higher level of IL-31RA protein compared to the duct portion.

Collectively, these data demonstrate that IL-31RA is expressed by epidermal keratinocytes from both control volunteers and AD patients. However, the levels of IL-31RA expressed on keratinocytes from AD skin biopsies were higher than the levels observed in skin biopsies from normal controls, indicating a potential for increased responsiveness to IL-31 in the context of AD.

IL-31RA was also found expressed on a subset of perivascular infiltrating cells present in skin biopsies from AD patients but was not present in control skin biopsies. These IL-31RA+ cells were recognized by an antibody specific for the tissue macrophage marker CD68, indicating these cells were skin-infiltrating tissue macrophages.

Example 8 Isolation of Skin Infiltrating Cells by Laser Capture Microscopy and Analysis of IL-31MRNA by RT-PCR

The presence of skin infiltrating T cells is a distinguishing feature in skin biopsies from AD patients compared to normal individuals. Since IL-31 is a T cell associated cytokine, the expression of IL-31 in skin-infiltrating T cells in tissue biopsies from AD patients was examined. First, the presence of increased numbers of CD3+ T cells in skin tissue biopsies from AD patients compared to normal individuals was confirmed by IHC. See Table 2. Next, laser capture microscopy was used to specifically isolate skin infiltrating cells for analysis of IL-31 mRNA by RT-PCR. IL-31 mRNA was expressed by skin infiltrating cells from acute AD patients. In normal tissues, infiltrating cells are not normally found and therefore could not be tested. However, the epidermal keratinocyte layer, which is present in both AD and normal skin, was analyzed for IL-31 mRNA expression and lower levels of IL-31 mRNA were found in normal samples compared to the epidermal keratinocyte layer of AD samples. Semi-quantitative analysis of IL-31 mRNA expression compared to an internal control gene (HPRT) showed that although IL-31 mRNA levels were not significantly different between AD and normal samples, there was a trend towards higher IL-31 expression in skin from AD patients.

Example 9 IL-31 is Produced by Memory T Cells with a Skin-Homing Phenotype

Analysis of skin biopsies confirmed that the infiltrating CD3+ T cells in the skin, which express IL-31 mRNA, express the skin-homing marker cutaneous lymphocyte antigen (CLA). Of the total T cell population in normal human peripheral blood, IL-31 expression was found to be largely restricted to CD45RO+ memory/effector cells as opposed to the CD45RA+ naïve T cell population.

In order to determine if IL-31 production was associated with CLA+ skin-homing T cells, CLA+ and CLA− T cells were isolated from peripheral blood of patients diagnosed with AD and control volunteers and compared IL-31 mRNA and protein levels following anti-CD3 plus anti-CD28 stimulation. Our results indicate that IL-31 mRNA was significantly elevated in CLA+ T cells from both AD and normal individuals at both 4 h (p0.0087 and p0.0022 CLA+ compared to CLA− for AD and normal, respectively) and 24 h (p0.0022 CLA+ compared to CLA− for both AD and normal samples) post stimulation. Analysis of IL-31 protein levels in culture supernatants confirmed that IL-31 was produced predominantly by CLA+ T cells as there was no detectible IL-31 in culture supernatants from CLA− T cells from both AD and control individuals. There were no significant differences in IL-31 levels between AD and normal patients. We also analysed the production of IL-31 by peripheral blood T cells that express other tissue-specific homing markers, such as the gut-specific homing marker α4β7, from normal volunteers. Comparison of the IL-31 levels produced by CLA+ T cells and α4β7+ cells demonstrated CLA+ T cells preferentially produce IL-31 compared to the α4β7+ cells (average of 34.5 pg/ml and 14.42 pg/ml IL-31, respectively).

Although both AD patients and normal controls have circulating CLA+ T cells that express IL-31 upon activation, CLA+ T cells from AD patients are reported to exist in a more activated state compared to cells from normal individuals. Consequently, the threshold of stimulation required for the production of IL-31 by CLA+ T cells may differ between dermatitis patients and control subjects. To test this hypothesis, we stimulated CLA+ T cells from AD patients and control individuals with sub-optimal concentrations of anti-CD3 in the absence of anti-CD28 and analyzed the production of IL-31 in culture supernatants at 24 h after stimulation. Our results demonstrate that circulating CLA+ T cells from some AD patients produce higher levels of IL-31 compared to cells from normal individuals in this study with maximum levels reaching 1200 pg/mL, whereas maximal detected levels in normal CLA+ supernatants was only 400 pg/ml and maximal detected levels for psoriasis patients was 73 pg/ml at suboptimal concentrations of anti-CD3 stimulation. Five of eleven AD patients showed IL-31 levels below the limit of detection of our assay suggesting there might be a subset of AD patients where IL-31 is produced at low levels. This may reflect variations in the stage of disease of our study population. Nevertheless, more than half of the AD patients showed a trend towards higher IL-31 levels compared to psoriasis patients and normal individuals following suboptimal stimulation with anti-CD3. Since more CLA+ T cells are localized in skin of AD patients as compared to normal individuals, our studies suggest that there is an increased potential for IL-31 activity in the AD skin micro-environment. Thus, this study may suggest a subpopulation of AD patients, which have more activated CLA+ T cells producing IL-31.

Example 10 Reduction of TARC and MDC in Response to Anti-Il-31 Antibody in AD Mouse Models

Method I

Six-week old male NC/Nga mice (CRL Japan) were sensitized intradermally with 50 μg dust mite extract (D. pteronyssinus, Indoor Biotechnologies) three times a week on the back and scored for AD-like lesions. After 5 weeks of sensitization the mice were euthanized and the right ears were excised and placed into a single well of a 48-well culture dish (Corning) supplemented with RPMI+2% FBS (GIBCO Invitrogen). Plates were placed in 5% CO2 humidity controlled incubators. Supernatants were collected after 24 hours and frozen at −20° C. until further analysis.

Method II

Twelve-week old female NC/Nga mice (CRL Japan) were sensitized intradermally with 10 μg SEB (Toxin Technology) in the ear and on the back three times per week. The mice were scored for AD-like lesions. After 5 weeks of sensitization the mice were euthanized and 6 mm biopsy punches were taken from the injected ear of each mouse and placed into a single well of a 48-well culture dish supplemented with RPMI+2% FBS. Plates were placed in 5% CO2 humidity controlled incubators. Supernatants were collected after 24 hours and frozen at −20° C. until further analysis.

Groups of mice in both studies were treated with either a rat anti-mouse IL-31 monoclonal antibody at 10 mg/kg or vehicle, intraperitoneally two times each week starting after 1 to 2 weeks of sensitization.

TARC and MDC concentrations in the 24-hour supernatant samples were measured by conventional ELISA (R&D Systems).

TARC and MDC concentrations were lower in ear supernatants from anti-IL-31 treated mice compared to control mice in both studies, however, these results were not statistically significant when analyzed by ANOVA, probably due to small sample size. When the data from both experiments is combined and analyzed there is a statistically significant difference between treated groups. 

1. A method of treating a patient suffering from a skin disorder, the method comprising: administering a therapeutically effective amount of an anti-IL-31RA antibody or fragment to the patient, wherein the anti-IL-31RA antibody or fragment binds with amino acid residues 20-519 of SEQ ID NO:6 or portion thereof, or amino acid residues 33-532 of SEQ ID NO:8 or portion thereof, and wherein the anti-IL-31RA antibody or fragment prevents, inhibits the progression of, delays the onset of, reduces the severity of, and/or inhibits at least one of the conditions or symptoms of the skin disorder selected from the group consisting of Atopic Dermititis, Contact dermatitis, Drug induced delayed type cutaneous allergic reactions, Toxic epidermal necrolysis, Cutaneous T cell Lymphoma, Bullous pemphigoid, Alopecia aereata, Vitiligo, Acne Rosacea, Prurigo nodularis, Scleroderma, and Herpes simplex virus.
 2. The method of claim 1 wherein the anti-IL-31RA antibody is a polyclonal antibody.
 3. The method of claim 1 wherein the anti-IL-31RA antibody is a neutralizing monoclonal antibody.
 4. A hybridoma which produces a monoclonal antibody according to claim
 3. 5. The method of claim 1 wherein the antibody fragment is a Fab fragment.
 6. The method of claim 1 wherein the antibody fragment is a Fab′ fragment.
 7. The method of claim 1 wherein the antibody fragment is a F(ab′)2 fragment.
 8. The method of claim 1 wherein the antibody fragment is a single chain Fv.
 9. The method of claim 1 wherein anti-IL-31RA antibody or fragment binds with amino acid residues 20-277 of SEQ ID NO:6 or 33-240 of SEQ ID NO:8.
 10. The method of claim 1 wherein the anti-IL-31RA antibody or fragment binds with about 4-10 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8.
 11. The method of claim 1 wherein the anti-IL-31RA antibody or fragment binds with about 10-14 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8.
 12. The method of claim 1 wherein the anti-IL-31RA antibody or fragment binds with about 14-30 amino acid residues of amino acid residues 20-519 of SEQ ID NO:6 or amino acid residues 33-532 of SEQ ID NO:8.
 13. The method of claim 1 wherein the fragment is further conjugated to a polyethylene glycol.
 14. The method of claim 1 wherein the fragment is further conjugated to human serum albumin.
 15. A method of treating a patient suffering from a skin disorder, the method comprising: administering a therapeutically effective amount of a soluble IL-31RA receptor to the patient, wherein the soluble IL-31RA receptor binds with an IL-31 polypeptide consisting of amino acid residues 1-164 SEQ ID NO:2, and wherein the soluble IL-31RA receptor prevents, inhibits the progression of, delays the onset of, reduces the severity of, and/or inhibits at least one of the conditions or symptoms of the skin disorder selected from the group consisting of Atopic Dermititis, Contact dermatitis, Drug induced delayed type cutaneous allergic reactions, Toxic epidermal necrolysis, Cutaneous T cell Lymphoma, Bullous pemphigoid, Alopecia aereata, Vitiligo, Acne Rosacea, Prurigo nodularis, Scleroderma, and Herpes simplex virus.
 16. The method of claim 15 wherein the soluble IL-31RA receptor comprises amino acid residues 20-519 of SEQ ID NO:6 or 33-240 of SEQ ID NO:8.
 17. The method of claim 15 wherein the soluble IL-31RA receptor comprises amino acid residues 1-324 of SEQ ID NO:10.
 18. The method of claim 15 wherein the soluble IL-31RA receptor comprises amino acid residues 1-239 of SEQ ID NO:12.
 19. The method of claim 15 wherein the soluble IL-31RA receptor is further conjugated to the Fc region of IgG, IgA, IgD, IgM or IgE.
 20. The method of claim 15 wherein the soluble IL-31RA receptor is an IL-31RA homodimer.
 21. The method of claim 15 wherein the soluble IL-31RA receptor is an IL-31RA/OSMRbeta heterodimer.
 22. The method of claim 15 wherein soluble IL-31RA receptor binds with an IL-31 polypeptide consisting of amino acid residues 24-164 of SEQ ID NO:2.
 23. The method of claim 15 wherein soluble IL-31RA receptor binds with an IL-31 polypeptide consisting of amino acid residues 27-164 of SEQ ID NO:2.
 24. The method of claim 15 wherein the soluble IL-31RA receptor is further conjugated to a polyethylene glycol.
 25. The method of claim 15 wherein the soluble IL-31RA receptor is further conjugated to human serum albumin. 